Strongly opposed to good person having copped it twice before (4,7)
I believe the answer is:
dead against
'strongly opposed' is the definition.
'good person having copped it twice before' is the wordplay.
I cannot really see how this works, but
'good' could be 'g' (abbreviation) and 'g' is found within the answer.
'person' could be 'dead' (dead person is a kind of person) and 'dead' is found in the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found within the answer.
This may be the basis of clue (or it may be nonsense).
'to' is the link.
(Other definitions for dead against that I've seen before include "Quite hostile to" , "Utterly opposed to (something)" , "Completely opposed to" .)