Monkey in trading centre eating some bananas (8)
I believe the answer is:
marmoset
'monkey' is the definition.
(marmoset is a kind of monkey)
'trading centre eating some bananas' is the wordplay.
'trading centre' becomes 'mart' (I've seen this before).
'eating' indicates putting letters inside.
'bananas' indicates anagramming the letters (informal term for mad).
'some' with letters rearranged gives 'mose'.
'mart' going around 'mose' is 'MARMOSET'.
'in' acts as a link.
(Other definitions for marmoset that I've seen before include "Star memo about kind of monkey" , "Small South American monkey" , "Take me to arms about bushy-tailed monkey of tropical America" , "Monkey with claws" , "Turn morse mat over for the monkey" .)