Intention to participate in regular payment for clothing (7)
I believe the answer is:
raiment
'clothing' is the definition.
(raiment is a kind of clothing)
'intention to participate in regular payment' is the wordplay.
'intention' becomes 'aim' ('aim' can be a synonym of 'intention').
'to participate in' means one lot of letters goes inside another.
'regular payment' becomes 'rent' (rent is a kind of regular payment).
'aim' going inside 'rent' is 'RAIMENT'.
'for' acts as a link.
(Other definitions for raiment that I've seen before include "Poetic word for clothing" , "Old word for fine clothing" , "Apparel" , "Attire" , "Am inert (anag) - clothing" .)