One who resists work with model? (7)
I believe the answer is:
opposer
'one who resists' is the definition.
(a person who opposes something)
'work with model?' is the wordplay.
'work' becomes 'op' (common abbreviation for 'opus').
'with' says to put letters next to each other.
'model?' becomes 'poser' ('poser' can be a synonym of 'model').
'op'+'poser'='OPPOSER'
(Other definitions for opposer that I've seen before include "The one against the motion" , "One resisting" , "Second to speak" , "One against something" , "Person against the motion" .)