Outfit starts off game at rock bottom (4)
I believe the answer is:
garb
'outfit' is the definition.
(I've seen this in another clue)
'starts off game at rock bottom' is the wordplay.
'starts off' says to take the initial letters.
The first letters of 'game at rock bottom' is 'GARB'.
(Other definitions for garb that I've seen before include "Clothes to brag about" , "Outfit" , "Raiment" , "Fashion of dress" , "something to wear" .)