I have a large file on the Clydesdale family in Ireland. Couldn't find anything on Alderdice, but found the following which may be "your" Robert:
Robert Clydesdale b. Aug 4 1864, Shanaghan, Banbridge (Birth Reg. Qtr. Rtn 1864, Vol. 16, p. 216). son of Robert Clydesdale and Margaret Keaney dau of Dennis Keaney
Robert Clydesdale b. Mar 24 1864, Glaskin, Loughbrickland (Birth Reg, Qtr Rtn, 1864, Vol. 6-1, p. 256). son of Alexander Clydesdale (Clidsdale) and Mary Jane McClain of Shanashbrill, dau of Joseph McClean.
If you are interested in my file, please let me know.