Being against work on preparing for photograph (8)
I believe the answer is:
opposing
'being against' is the definition.
('oppose' can be a synonym of 'be against')
'work on preparing for photograph' is the wordplay.
I cannot really see how this works, but
'work' could be 'op' (common abbreviation for 'opus') and 'op' is found within the answer.
The remaining letters 'posing' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for opposing that I've seen before include "trying to end a sea of troubles by it?" , "Disapproving" , "modelling after work" , "Contending" , "Going against" .)