Deck officer's outside, cut (5)
I believe the answer is:
orlop
'deck' is the definition.
(orlop is a kind of deck)
'officer's outside cut' is the wordplay.
'outside' means to remove the middle letters.
'cut' becomes 'lop' (lopping is a kind of cutting**).
'officer' with its centre taken out is 'or'.
'or'+'lop'='ORLOP'
(Other definitions for orlop that I've seen before include "part of ship" , "Ship's lowest deck" , "deck at the lowest point" , "hold covering" , "Lowest deck of a wooden sailing ship" .)