Work in a shop usually (4)
I believe the answer is:
opus
'work' is the definition.
(I've seen this before)
'in a shop usually' is the wordplay.
'in' says the answer is hidden in the clue.
'OPUS' can be found hidden inside 'a shop usually'.
(Other definitions for opus that I've seen before include "Work (mus.)" , "Creative work, eg in writing, art or music" , "Musical composition in the soup" , "Artistic work" , "Work of 25 perhaps" .)