Prize fighter rubs one the wrong way, generous at heart (7)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

Anagram (the wrong way) of RUBS + I (one in Roman numerals), then the middle letters (heart) of [gen] ER [ous]. Prize fighter = someone who takes part in a fight or boxing match to win money; bruiser = someone big and tough who is easily drawn into a fight, or (according to Chambers) another word for a prize fighter.