Turning slates for photograph (4)
I believe the answer is:
snap
'for photograph' is the definition.
(synonyms)
'turning slates' is the wordplay.
'turning' says the letters should be written backwards.
'slates' becomes 'pans' (both can mean criticises).
'pans' written backwards gives 'SNAP'.
(Other definitions for snap that I've seen before include "Unpremeditated - bite" , "Cut" , "you may take on holiday" , "piece of cake" , "Break; bite suddenly" .)