Garment in a fashionable company stolen by cad (8)
I believe the answer is:
raincoat
'garment' is the definition.
(raincoat is a kind of garment)
'a fashionable company stolen by cad' is the wordplay.
'fashionable' becomes 'in' (in can mean fashionable or trendy).
'company' becomes 'co' (abbreviation).
'stolen by' indicates putting letters inside (inserted letters are taken or stolen).
'cad' becomes 'rat' (I've seen this before).
'a'+'in'+'co'='ainco'
'ainco' going within 'rat' is 'RAINCOAT'.
'in' acts as a link.
(Other definitions for raincoat that I've seen before include "Water-resistant outer garment" , "Wet weather gear" , "Wet weather wear" , "Protective garment for Croatian" , "Waterproof outer garment" .)