Nautical cry (4)
I believe the answer is:
ahoy
'nautical cry' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ahoy that I've seen before include "Seafarer's call" , "Hail at sea" , "What a sailor may" , "Hailing term at sea" , "Cry at sea" .)