Work time into composition (5)
I believe the answer is:
opera
'composition' is the definition.
(thesaurus)
'work time' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'time' becomes 'era' (era is a kind of time).
'op'+'era'='OPERA'
'into' is the link.
(Other definitions for opera that I've seen before include "Eg, Il trovatore" , "Eg, Der Rosenkavalier" , "Stage entertainment" , "Carmen, perhaps" , "Norma is one" .)