The IGI
https://familysearch.org/search/collection/igi lists 9 children of Alexander Cleland and Margaret Forbes
Robert, baptised 5 Aug 1808, Kilsyth
Duncan, baptised 25 Feb 1810, Kilsyth
Duncan, baptised 9 Feb 1812, Bothkennar, Stirlingshire
Alexander, baptised 6 March 1820, Kilsyth
John, baptised 17 Feb 1822, Kilsyth
Janet and James, baptised 25 July 1824, Kilsyth
Andrew, baptised 1 April 1827, Kilsyth
David, baptised 16 August 1829, Kilsyth
There are a couple of oddities about this. First, why was the second Duncan (presumably the first one had died) baptised in Bothkennar? And second, there is a gap of 8 years between Alexander and John. Were there no more children, or were there others whose baptism records have not survived?
Note that the eldest son was named Robert and the second son was Duncan. So it would be reasonable to expect Alexander's father to be Robert and Margaret's to be Duncan.
I see that in the 1851 census transcription at FreeCEN
http://www.freecen.org.uk/cgi/search.pl there is a Clelland family at Hilton Cottages, Cadder consisting of Alexander, 66, iron miner, born Kilsyth, wife Margaret, 64, born Callander, Perthshire, sons Andrew, 24 and David, 21, and grandson Alexander, 9.
In the 1841 census Andrew Cleland, 14 and David Cleland, 11, were servants in the household of Thomas Duncan, Wester Duletor (now spelled Dullatur), Cumbernauld.
Alex Clelland, 50, Margaret, 5, James, 13, Christian, 20 and Janet, 13, were at Bridge end, Kilsyth. I would want to look at the original of this, because it looks as if Margaret's age is wrong. James and Janet's ages are spot on. Christian is interesting. In 1841, ages of those over 15 were supposed to be rounded down to the nearest 5 years. So Christian would have been born between 7 June 1816 and 6 June 1821 - exactly in the gap in the baptisms above.
Presumably you have already got the death certificates of Alexander Clelland (d 1869) and Margaret Forrest or Clelland (d 1862) so you know the names of their parents?
From the census it looks as if Alexander might have been the son of Robert Clelland and Janet Finlay, baptised in Kilsyth on 25 January 1784.
The IGI lists 8 sons of Robert and Janet
David, baptised 18 Feb 1770
John, baptised 12 April 1772
Andrew, baptised 27 Dec 1773
James, baptised 14 July 1776
Robert, baptised 8 June 1781
Alexander, baptised 25 Jan 1784
William, baptised 5 August 1787
Peter, baptised 2 Jan 1791
Odd that there are no daughters listed. On the other hand, the IGI is notoriously unreliable, being neither 100% comprehensive nor 100% accurate. There are parishes where whole swathes of records were missed out of the IGI, and even some where baptism of one sex are listed but not those of the other sex. As always with the IGI, I would plan to look at the original records, either on Scotland's People or on microfilm at a local LDS Church Family History Centre.
The IGI also says that Robert Cleland, son of David Cleland and Jean Laing, was baptised in Kilsyth in 1742. This looks credible (Robert's eldest son seems to have been David) but I would not trust this information - I'd want to track down where it came from before believing it.
Cadder does belong to Lanarkshire, barring the odd minor boundary change. Glasgow is in the county of Lanark, also known as Lanarkshire (but never 'County Lanark' or 'Lanark County'), and not to be confused with the burgh (town) and parish of Lanark, from which the county takes its name. (The burgh is within the parish and the parish is within the county.)
There is useful information about which parishes are where in Lanarkshire at
http://www.genuki.org.uk/big/sct/LKS/As background reading, the Statistical Accounts of Scotland, are online at
http://edina.ac.uk/stat-acc-scot/ - use the 'Brows scanned pages' link to avoid having to sign up. These are a set of descriptions of the topography, population, history and economic activity of every parish in Scotland, the original one written in the 1790s and the New Statistical Account in the 1830s.