Keep your head down for nothing (4)

I believe the answer is:

duck

This clue is a double definition.

'keep your head down' is the first definition.

'nothing' is the second definition.
(thesaurus)

'for' acts as a link.

(Other definitions for duck that I've seen before include "Quacker?" , "What represents zero score" , "sails material" , "Use one's wits to get something" , "Dear; bird; fabric" .)

I've seen this clue in The Guardian.

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