Worn-out clothing that is frayed at the back (7)
I believe the answer is:
wearied
'worn' is the definition.
('weary' can be a synonym of 'wear')
'out clothing that is frayed at the back' is the wordplay.
'out clothing' becomes 'wear' (synonyms. I am not sure about the 'out' bit.).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'at the back' says to take the final letters.
The last letter of 'frayed' is 'd'.
'wear'+'ie'+'d'='WEARIED'
Can you help me to learn more?
(Another definition for wearied that I've seen is " Tired, exhausted".)