Work in shop usually (4)
I believe the answer is:
opus
'work' is the definition.
(an opus is an artistic work)
'in shop usually' is the wordplay.
'in' indicates the answer is hidden within the clue.
'OPUS' can be found hidden inside 'shop usually'.
(Other definitions for opus that I've seen before include "(Numbered) musical composition" , "Work of 25 perhaps" , "Showing creative skill" , "Work or composition, usually musical" , "Work (mus.)" .)