Pigs a man butchered in alternative religion (8)
I believe the answer is:
paganism
'alternative religion' is the definition.
'paganism' can be an answer for 'religion' (paganism is a kind of religion). I am not sure about the 'alternative' bit.
'pigs a man butchered' is the wordplay.
'butchered' indicates an anagram (I've seen this in other clues).
'pigs'+'a'+'man'='pigsaman'
'pigsaman' with letters rearranged gives 'PAGANISM'.
'in' is the link.
Can you help me to learn more?
(Other definitions for paganism that I've seen before include "Irreligious behaviour" , "Belief; man as pig (anag.)" , "irreligious practices" , "Man's a pig (anag.)" , "Religion" .)