Where he is involved in a diverting treat? (7)
I believe the answer is:
theatre
'where' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'he is involved in a diverting treat?' is the wordplay.
'is involved in' is an insertion indicator.
'a diverting' indicates anagramming the letters (letters diverted elsewhere).
'treat' anagrammed gives 'tatre'.
'he' put within 'tatre' is 'THEATRE'.
Can you help me to learn more?
(Other definitions for theatre that I've seen before include "Major area of military activity" , "where they're in action?" , "(Lecture) room" , "Hospital operating room - playhouse" , "Play scene" .)