Rude about ship in force (6)
I believe the answer is:
duress
'force' is the definition.
(duress is a kind of force)
'rude about ship' is the wordplay.
'about' is an anagram indicator.
'ship' becomes 'ss'.
'rude' with letters rearranged gives 'dure'.
'dure'+'ss'='DURESS'
'in' acts as a link.
(Other definitions for duress that I've seen before include "Restraint" , "Coercion, compulsion" , "Compulsory force or threat" , "Pressure applied by druses" , "Coercion, pressure" .)