'Hello sailor' appropriate? (6)
I believe the answer is:
hijack
'appropriate?' is the definition.
(I've seen this before)
'hello sailor' is the wordplay.
'hello' becomes 'hi' (synonyms).
'sailor' becomes 'jack' (informal term for a sailor).
'hi'+'jack'='HIJACK'
(Other definitions for hijack that I've seen before include "Appropriate" , "Criminal seizure of plane" , "Steal en route" , "Take over plane by force in flight" , "Seize a vehicle illegally" .)