Crime for which priest is beheaded? (5)
I believe the answer is:
arson
'crime' is the definition.
(I've seen this before)
'priest is beheaded?' is the wordplay.
'priest' becomes 'parson'.
'is beheaded?' means to remove the first letter (the head of the word is removed).
'parson' with its initial letter removed is 'ARSON'.
'for which' acts as a link.
(Other definitions for arson that I've seen before include "Criminal burning of property" , "Be pettish" , "Iniquitous behaviour" , "Pyromaniac crime" , "major crime" .)