Criminal warrant you truncated for a pest (6,3)
I believe the answer is:
norway rat
'pest' is the definition.
(I've seen this before)
'criminal warrant you truncated' is the wordplay.
'criminal' is an anagram indicator.
'truncated' means to remove the last letter.
'warrant'+'you'='warrantyou'
'warrantyou' with its final letter taken off is 'warrantyo'.
'warrantyo' is an anagram of 'NORWAY RAT'.
'for a' acts as a link.
(Other definitions for norway rat that I've seen before include "Common pest" , "Quisling was" .)