A huge word of warning to sailors (5)

I believe the answer is:

avast

'word of warning to sailors' is the definition.
(nautical term meaning 'stop')

'a huge' is the wordplay.
'huge' becomes 'vast' (I've seen this before).
'a'+'vast'='AVAST'

(Other definitions for avast that I've seen before include "Stop at sea" , "shout stopping the ship" , "Hold fast! (naut.)" , "Stop (nautical)" , "Stop! (naut.)" .)

I've seen this clue in The Telegraph.

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