Heading to puritanical relations can be hell (3)
I believe the answer is:
pit
'be hell' is the definition.
('the pit' can mean hell)
'heading to puritanical relations' is the wordplay.
'heading to' indicates taking the first letters (the head of the word).
'relations' becomes 'it' (both can mean sex).
The initial letter of 'puritanical' is 'p'.
'p'+'it'='PIT'
'can' is the link.
(Other definitions for pit that I've seen before include "Hollow" , "Quarry" , "Mine; fruit stone" , "Place for the accompanying orchestra" , "Deep hole (in theatre?)" .)