One scoring equaliser in state, restricting England (7)
I believe the answer is:
avenger
'one scoring equaliser' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'state restricting england' is the wordplay.
'state' becomes 'aver' (both can mean to declare).
'restricting' means one lot of letters goes inside another.
'england' becomes 'eng' (abbreviation).
'aver' placed around 'eng' is 'AVENGER'.
'in' is the link.
Can you help me to learn more?
(Other definitions for avenger that I've seen before include "One inflicting retribution" , "One exacts retribution" , "One who retaliates -- engrave (anag)" , "One who gets even" , "Mrs Peel?" .)