Crossword Genius

Master Charlie's raincoat (3)

Ross

I believe the answer is:

mac

'raincoat' is the definition.
(macintosh is a type of raincoat)

'master charlie's' is the wordplay.
'master' becomes 'ma' (Master of Arts).
'charlie' becomes 'C' (phonetic alphabet: alpha, bravo, charlie etc.).
'ma'+'c'='MAC'

(Other definitions for mac that I've seen before include "A Gaelic son, often in name" , "one used in shower?" , "Waterproof coat (colloq.)" , "Waterproof raincoat, in short" , "laptop?" .)

I've seen this clue in the Evening Standard.
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