Part of hero is terrific romp (7)
I believe the answer is:
roister
'part' is the definition.
The answer and definition can be both to do with social activities as well as being verbs in their base form.
Perhaps you can see a link between them that I don't see?
'of hero is terrific romp' is the wordplay.
'of' indicates a hidden word.
'ROISTER' is hidden in the letters of 'hero is terrific romp'.
Can you help me to learn more?
(Other definitions for roister that I've seen before include "Noisy reveller" , "Carouse" , "Enfold" , "Have noisy fun" , "Celebrate noisily" .)