Rubbish clothing on a golf course, ultimately (7)
I believe the answer is:
garbage
'rubbish' is the definition.
(both can mean refuse or trash)
'clothing on a golf course ultimately' is the wordplay.
'clothing' becomes 'garb' (garb is a kind of clothing).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'ultimately' says to take the final letters.
The final letter of 'course' is 'e'.
'garb'+'a'+'g'+'e'='GARBAGE'
(Other definitions for garbage that I've seen before include "A beggar? - that may be rubbish" , "Rubbish, waste" , "Refuse - a beggar (anag)" , "'Refuse, rubbish (7)'" , "hot air" .)