Table ornament kept in centre by green bananas (7)
I believe the answer is:
epergne
'table ornament' is the definition.
(I've seen this before)
'kept in centre by green bananas' is the wordplay.
'in centre' says to take the centre.
'by' is a charade indicator (letters next to each other).
'bananas' is an anagram indicator (bananas can informally mean crazy).
The central letters of 'kept' are 'ep'.
'green' is an anagram of 'ergne'.
'ep'+'ergne'='EPERGNE'
(Other definitions for epergne that I've seen before include "Ornamental fruit- holding centrepiece for table" , "ornament on board" , "Table ornament with small bowls on branched supports" , "Large centrepiece" , "Table-centre stand" .)