On deck, maybe, stop sweeping after area (5)
I believe the answer is:
avast
'on deck maybe stop' is the definition.
I can't judge whether this defines the answer.
'sweeping after area' is the wordplay.
'sweeping' becomes 'vast' (I've seen this in another clue).
'after' means one lot of letters go next to another.
'area' becomes 'a' (maths abbreviation).
'vast' after 'a' is 'AVAST'.
Can you help me to learn more?
(Other definitions for avast that I've seen before include "Stop on board" , "Stop, nautically speaking" , "eleven [CEASE] at sea" , "Stop! (naut.)" , ""stop" signal" .)