Clothes start to look old rubbish (7)
I believe the answer is:
garbage
'rubbish' is the definition.
(both can mean refuse or trash)
'clothes start to look old' is the wordplay.
'clothes' becomes 'garb' (garb is a kind of clothes).
'start to look old' becomes 'age' (to age is to get older).
'garb'+'age'='GARBAGE'
(Other definitions for garbage that I've seen before include "Rubbish, waste" , "Litter" , "Brag about age? - that's rubbish" , "A beggar? - that may be rubbish" , "hot air" .)