Hat raised to some of one's mates (3)

I believe the answer is:

tam

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'hat' is the definition.
(thesaurus)

I cannot understand how the remainder of the clue works.

(Other definitions for tam that I've seen before include "'Scottish cloth cap, in short (3)'" , "'Woollen cap of Scottish origin, in short (3)'" , "Scotsman's cap" , "Headgear" , "Ratings compiled on TV listener numbers" .)

I've seen this clue in the Evening Standard.

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