Best garment (3)
I believe the answer is:
top
I believe this clue is a double definition.
'best' is the first definition.
('top' is associated in meaning with 'best')
'garment' is the second definition.
(top is a kind of garment)
(Other definitions for top that I've seen before include "SECOND PART OF 10 ACROSS" , "Peak; child's toy" , "Kill" , "Toy; uppermost point" , "Upper side" .)