Hunting animal, report a criminal pinching diamonds (8)
I believe the answer is:
predator
'hunting animal' is the definition.
(I've seen this before)
'report a criminal pinching diamonds' is the wordplay.
'criminal' is an anagram indicator.
'pinching' means one lot of letters goes inside another (taking inside).
'diamonds' becomes 'd' (abbreviation in bridge say).
'report'+'a'='reporta'
'reporta' with letters rearranged gives 'preator'.
'preator' going around 'd' is 'PREDATOR'.
(Other definitions for predator that I've seen before include "Seeker of prey" , "eagle, say" , "Beast which preys on another" , "Parroted like one who exploits others" , "Animal preying on others" .)