Choose a work-shirt (3)
I believe the answer is:
opt
'choose' is the definition.
(both can mean to pick something)
'a work-shirt' is the wordplay.
'a work' becomes 'op' (abbreviation for opus).
'shirt' becomes 't' (as in a T-shirt).
'op'+'t'='OPT'
(Other definitions for opt that I've seen before include "Decide between possibilities, choose" , "Hold in the highest esteem" , "Elect" , "End or act of shutting" , "Have preference for something" .)