A night in Paris covered by city pension (7)
I believe the answer is:
annuity
'pension' is the definition.
(thesaurus)
'a night in paris covered by city' is the wordplay.
'night in paris' becomes 'nuit'.
'covered by' indicates putting letters inside.
'city' becomes 'ny' (I've seen this in other clues).
'nuit' placed inside 'ny' is 'nnuity'.
'a'+'nnuity'='ANNUITY'
(Other definitions for annuity that I've seen before include "Yearly payment" , "Pension investment" , "Form of investment" , "guaranteed payment" , "Pension arrangement" .)