Rent to the Royal Navy (4)
I believe the answer is:
torn
'rent' is the definition.
('torn' can be a synonym of 'rent')
'to the royal navy' is the wordplay.
'the royal navy' becomes 'rn'.
'to'+'rn'='TORN'
(Other definitions for torn that I've seen before include "Divided" , "Removed forcibly" , "In a state of uncertainty between two conflicting options" , "Lacerated - in two minds" , "Having rips" .)