A biblical extract that's intractable (8)
I believe the answer is:
perverse
'intractable' is the definition.
(I've seen this before)
'a biblical extract' is the wordplay.
'a' becomes 'per' (eg 'one a day' means 'one per day').
'biblical extract' becomes 'verse' (verse of the Bible).
'per'+'verse'='PERVERSE'
'that's' is the link.
(Other definitions for perverse that I've seen before include "'Wayward, peevish (8)'" , "'Contrary to what's considered right, proper or good (8)'" , "'Unreasonable, awkward (8)'" , "Cussed" , "Deliberately departing from what is reasonable" .)