Do more than check the ship's officer (4)
I believe the answer is:
mate
I believe this clue is a double definition.
'do more than check' is the first definition.
(I've seen this in another clue)
'ship's officer' is the second definition.
(mate is a kind of ship's officer)
'the' acts as a link.
(Other definitions for mate that I've seen before include "When one can no longer play" , "Freind, companion" , "Fellow member, partner" , "Match" , "couple" .)