Somehow limit a time when filling in summary (4-3)
I believe the answer is:
rate-cap
'somehow limit' is the definition.
(to rate-cap once meant to limit leviable rates)
'a time when filling in summary' is the wordplay.
'time' becomes 't'.
'when filling in' indicates putting letters inside.
'summary' becomes 'recap' (recap is a kind of summary).
'a'+'t'='at'
'at' put into 'recap' is 'RATE-CAP'.
(Other definitions for rate-cap that I've seen before include "Government limit on local authority levy" , "Limit put by central government on local authority charges" , "Levy limiter" , "limit, sort of" .)