Regular payment: some should cover night in Paris (7)
I believe the answer is:
annuity
'regular payment' is the definition.
(annuity is a kind of regular payment)
'some should cover night in paris' is the wordplay.
'some' becomes 'any' (similar in meaning).
'should cover' means one lot of letters goes inside another.
'night in paris' becomes 'nuit' ('night' in French).
'any' placed around 'nuit' is 'ANNUITY'.
(Other definitions for annuity that I've seen before include "Yearly payment" , "guaranteed payment" , "Pension investment" , "Regular income from a fund" , "Pension arrangement" .)