I had a good rake about in the Valuation Rolls and the Post Office directories for Forfar.
There was (1) Alexander Clark, factory worker, who lived in various houses around the west end of the town from 1886 onwards. I think he can be discounted.
(2) Alexander Clark, mason, was at 22 Arbroath Road in 1886 and 1887, and at Toyhillock in 1892. This is the only mention I can find in either the VRs or the PO directories of an Alexander Clark in Toyhillock.
(3) Alexander Clark, turner, was at 5 Prior Road 1892-1893, 1 Prior Road 1893-1894 and 1902, 40 Prior Road in 1895 and 6 Arbroath Road 1898-1900.
(2) and (3) are definitely not the same person, because they are both listed in the 1892 PO directory.
(4) There remain listings of Alexander Clark with various occupations - weaver, carter, packman - at Headingstone Place (various spellings) whch is sometimes listed as in Prior Road and sometimes not. He is in 1 William Street in 1894 and 3 William Street 1895-1897.
I looked for other people whose address was sometimes given as Toyhillock. One was a Samuel Easson, described in the street directories as a carter, who was at 41 Prior Road from 1885-1901 (except for one year when it was listed as 44 Prior Road), then at 13 Headingstone Place, 41 Prior Road 1902-1911, except for 1907 when the PO directory listed him at Toyhillock. I have to ask myself whether Toyhillock was a clerical error, but if not, it might pinpoint Toyhillock.
There were other people listed in the street directories at Toyhillock - John Samson, mason; Alexander McFarlane, factory wroker; James Macdougall, factory worker; David Ross, factory worker; David Christie, night watchman; James Mictchell, joiner; Alexander Adamson, labourer; and Edward Campbell, carter. I have not yet looked in detail at any of these. (Breakfast calls!)