Garment chap's put in sink (6)
I believe the answer is:
sarong
'garment' is the definition.
(sarong is a kind of garment)
'chap's put in sink' is the wordplay.
'chap' becomes 'ron' (**).
'put in' means one lot of letters goes inside another.
'sink' becomes 'sag' (sagging is a kind of sinking).
'ron' going within 'sag' is 'SARONG'.
(Other definitions for sarong that I've seen before include "Brightly-coloured Asian skirt" , "Wrapped dress or skirt" , "Brightly-coloured skirt in the South Pacific" , "Asian skirt-like garment" , "SE Asian garment" .)