Stop insect consuming banana's insides (9)
I believe the answer is:
terminate
'stop' is the definition.
(terminate can mean to stop or bring to an end)
'insect consuming banana's insides' is the wordplay.
'insect' becomes 'termite' (termite is a kind of insect).
'consuming' indicates putting letters inside.
'insides' indicates the central letters (I've seen 'inside' mean this).
The middle of 'banana' is 'na'.
'termite' placed around 'na' is 'TERMINATE'.
(Other definitions for terminate that I've seen before include "Close" , "Put an end to, discontinue" , "Stop" , "Conclude" , "Bring to an end" .)