Old clothes split without intention (7)
I believe the answer is:
raiment
'old clothes' is the definition.
'raiment' can be an answer for 'clothes' (raiment is a kind of clothes). I am not sure about the 'old' bit.
'split without intention' is the wordplay.
'split' becomes 'rent' (past tense of 'rend' meaning to split).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'intention' becomes 'aim' (synonyms).
'rent' enclosing 'aim' is 'RAIMENT'.
Can you help me to learn more?
(Other definitions for raiment that I've seen before include "Clothing (archaic)" , "Apparel" , "Especially fine or decorative clothing" , "these garments are old-fashioned" , "investment" .)