Heartless freethinker engages chaps joining English university about biblical interpretation (11)
I believe the answer is:
hermeneutic
'about biblical interpretation' is the definition.
'heartless freethinker engages chaps joining english' is the wordplay.
'heartless' says to hollow out the word (remove centre letters).
'freethinker' becomes 'heretic'.
'engages' means one lot of letters goes inside another.
'chaps' becomes 'men' (I've seen this before).
'joining english' becomes 'eu' (I can't justify this - if you can you should believe this answer much more).
'heretic' with its middle removed is 'hertic'.
'men'+'eu'='meneu'
'hertic' enclosing 'meneu' is 'HERMENEUTIC'.
'university' is the link.
I am not very happy about this link. It may belong to another bit of the clue.