Change part of play in religious festival (8)
I believe the answer is:
passover
'religious festival' is the definition.
(I've seen this before)
'change part of play' is the wordplay.
'change' becomes 'pass' (passing is a kind of changing).
'part of play' becomes 'over' (I am not sure about this - if you are sure you should believe this answer much more).
'pass'+'over'='PASSOVER'
'in' is the link.
Can you help me to learn more?
(Other definitions for passover that I've seen before include "religious festival" , "Disregard - Jewish festival" , "spring festival" , "feast - with 25a" .)