Stand up to model after work (6)
I believe the answer is:
oppose
'stand up to' is the definition.
(I've seen this in another clue)
'model after work' is the wordplay.
'model' becomes 'pose' (model can mean to pose).
'after' says to put letters next to each other.
'work' becomes 'op' (abbreviation for opus).
'pose' after 'op' is 'OPPOSE'.
(Other definitions for oppose that I've seen before include "Counter" , "Resist, contend with" , "Act against" , "Compete with" , "Argue against" .)