Placate monkey eating small round things (7)
I believe the answer is:
appease
'placate' is the definition.
(synonyms)
'monkey eating small round things' is the wordplay.
'monkey' becomes 'ape' (I've seen this before).
'eating' means one lot of letters goes inside another.
'small round things' becomes 'peas' (small round vegetables).
'ape' going around 'peas' is 'APPEASE'.
(Other definitions for appease that I've seen before include "Propitiate by concessions" , "Make calm by offering concessions" , "Placate (someone) by agreeing to their demands" , "be satisfying" , "Quiet" .)