Some chap in a foreign garment (8)
I believe the answer is:
pinafore
'garment' is the definition.
(pinafore is a kind of garment)
'some chap in a foreign' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'PINAFORE' is hidden in the letters of 'chap in a foreign'.
(Other definitions for pinafore that I've seen before include "'HMS - - ' G & S" , "Protective garment; a stage ship" , "Musical craft" , "Stagecraft, say" , "Sleeveless dress or apron" .)