Garment, unique, bought at last (7)
I believe the answer is:
singlet
'garment' is the definition.
(singlet is a kind of garment)
'unique bought at last' is the wordplay.
'unique' becomes 'single' (similar in meaning).
'at last' suggests the final letters.
The last letter of 'bought' is 't'.
'single'+'t'='SINGLET'
(Other definitions for singlet that I've seen before include "Sleeveless vest" , "Sleeveless garment" , "top gear" , "Sleeveless shirt" , "garment worn by men" .)