Three months in this district (7)
I believe the answer is:
quarter
I believe this clue is a double definition.
'three months' is the first definition.
(I've seen this before)
'this district' is the second definition.
(quarter is a kind of district)
'in' is the link.
(Other definitions for quarter that I've seen before include "Residence - mercy" , "Fourth; mercy" , "Neighbourhood" , "US coin" , "Fractional mercy towards opponent?" .)