Also a kind of shirt and a pair of spectacles (3)
I believe the answer is:
too
'also' is the definition.
(I know that also can be written as too)
'a kind of shirt and a pair of spectacles' is the wordplay.
'a kind of shirt' becomes 'T' (T-shirt).
'and' means one lot of letters go next to another.
'a pair of spectacles' becomes 'OO' (OO looks like spectacles).
't'+'oo'='TOO'
(Other definitions for too that I've seen before include "Moreover, in addition" , "What a pity!" , "As well, also" , "Furthermore" , "On top - also" .)