Play against work model (6)
I believe the answer is:
oppose
'play against' is the definition.
(as in being on the opposing team)
'work model' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'model' becomes 'pose' (synonyms).
'op'+'pose'='OPPOSE'
(Other definitions for oppose that I've seen before include "Compete with" , "Refute - confront" , "Act against" , "match" , "Resist (someone)" .)