Concur — a craving must be curtailed (5)
I believe the answer is:
agree
'concur' is the definition.
(synonyms)
'a craving must be curtailed' is the wordplay.
'craving' becomes 'greed' (I've seen this before).
'must be curtailed' means to remove the last letter (the word is trimmed or curtailed).
'greed' with its final letter taken away is 'gree'.
'a'+'gree'='AGREE'
(Other definitions for agree that I've seen before include "Concur, coincide" , "Think alike" , "Give consent" , "Accept" , "Settle" .)