Crime first off with purpose creates basis for discussion (7,5)
I believe the answer is:
talking point
'basis for discussion' is the definition.
(something to talk about)
'crime first off with purpose' is the wordplay.
I cannot quite see how this works, but
'first' could be 'i' (I in Roman numerals eg Elizabeth I) and 'i' is found in the answer.
'purpose' could be 'point' (I've seen this before) and 'point' is present in the answer.
This explanation may well be incorrect...
'creates' is the link.
(Other definitions for talking point that I've seen before include "matter for debate" , "Subject for discussion" , "Topic inviting discussion" , "Matter of discussion" .)