Folk hero's bonnet (4)

I believe the answer is:

hood

This clue is a double definition.

'folk hero's' is the first definition.
(Robin Hood)

'bonnet' is the second definition.
(synonyms)

(Other definitions for hood that I've seen before include "Head covering of an American gangster" , "Part of subfusc" , "academic garment" , "A cover; Bismarck sank it, 1941" , "this could provide cover" .)

I've seen this clue in The Guardian.

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