Sound made by chosen Caledonian tribesman (4)
I believe the answer is:
pict
'caledonian tribesman' is the definition.
(Picts were an ancient people)
'sound made by chosen' is the wordplay.
'sound made by' indicates a 'sounds like' (homophone) clue.
'chosen' becomes 'picked' (picking is a kind of choosing).
'picked' sounds like 'PICT'.
(Other definitions for pict that I've seen before include "Literary term for painted woman" , "Ancient Scot in Roman times" , "Very old person" , "Northerner" , "Ancient north Briton" .)