Steal bananas in smallest amount (5)
I believe the answer is:
least
'smallest amount' is the definition.
(I've seen this before)
'steal bananas' is the wordplay.
'bananas' is an anagram indicator (informal term for mad).
'steal' is an anagram of 'LEAST'.
'in' acts as a link.
(Other definitions for least that I've seen before include "No more petty" , "Smallest (in significance)" , "Most insignificant" , "Most slight" , "Lowest amount" .)