In sea RN ship pulls in (5)
I believe the answer is:
earns
'pulls in' is the definition.
('earn' can be a synonym of 'pull in')
'in sea rn ship' is the wordplay.
'in' indicates the answer is hidden within the clue.
'EARNS' is hidden in the letters of 'sea rn ship'.
(Other definitions for earns that I've seen before include "Merits through work" , "ready for work?" , "Grosses" , "Acquires by effort" , "Makes - deserves (by one's efforts)" .)