Right to take part in stupid sketch (5)
I believe the answer is:
draft
'sketch' is the definition.
(draft is a kind of sketch)
'right to take part in stupid' is the wordplay.
'right' becomes 'r' (common abbreviation).
'to take part in' means one lot of letters goes inside another.
'stupid' becomes 'daft' (I've seen this before).
'r' put inside 'daft' is 'DRAFT'.
(Other definitions for draft that I've seen before include "Preliminary version or sketch" , "Rough sketch" , "Sketch; money order" , "Sketch - detachment of men" , "select group" .)