Do what's required in topping role? (6)
I believe the answer is:
behead
'do' is the definition.
Although both the answer and definition are verbs in their base form, I don't see how they can define each other.
'what's required in topping role?' is the wordplay.
'what' becomes 'eh' (sound used to ask 'what?' or 'pardon?').
'required in' indicates putting letters inside.
'topping role?' becomes 'bead' (I can't justify this - if you can you should believe this answer much more).
'eh' going into 'bead' is 'BEHEAD'.
Can you help me to learn more?
(Other definitions for behead that I've seen before include "wield the axe" , "Knock someone's block off?" , "Decapitate" , "Knock one's block off!" , "Remove cranium as in old execution" .)