Help island cutting bananas (4)
I believe the answer is:
maid
'help' is the definition.
(help can mean servants)
'island cutting bananas' is the wordplay.
'island' becomes 'i' (geographical abbreviation).
'cutting' means one lot of letters goes inside another (some letters cut their way into a word).
'bananas' becomes 'mad' (slang for insane).
'i' inserted inside 'mad' is 'MAID'.
(Other definitions for maid that I've seen before include "Female domestic servant" , "Serving girl" , "One in service" , "Young woman - servant" , "Female servant - young girl" .)