Condemns senescent criminal (9)
I believe the answer is:
sentences
'condemns' is the definition.
('sentence' can be a synonym of 'condemn')
'senescent criminal' is the wordplay.
'criminal' is an anagram indicator.
'senescent' anagrammed gives 'SENTENCES'.
(Other definitions for sentences that I've seen before include "Judicial penalties" , "Judicial punishments or words arrangements" , "Word sets of senescent origin" , "Declares punishment for" , "Words with grammatical structures" .)