Vaunt oneself in strange garb (4)

I believe the answer is:

brag

I'm a little stuck... Click here to teach me more about this clue!

'vaunt' is the definition.
(I know that vaunt can be written as brag)

'oneself in strange garb' is the wordplay.
'garb' anagrams to 'BRAG'.
But, I'm unsure how this is indicated.

Can you help me to learn more?

(Other definitions for brag that I've seen before include "Boast ? card-game" , "game of bluff" , "Talk boastfully" , "Card game - boast" , "boast; form of poker" .)

I've seen this clue in the Evening Standard.

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