Very unconventional means of leaving (3,3)
I believe the answer is:
way out
'very unconventional' is the definition.
'way out' can be an answer for 'unconventional' (I've seen this before). I am unsure of the 'very' bit.
'means of leaving' is the wordplay.
'means' becomes 'way' (a way or means of doing something).
'of leaving' becomes 'out' (I can't explain this - if you can you should believe this answer much more).
'way'+'out'='WAY-OUT'
Can you help me to learn more?
(Other definitions for way out that I've seen before include "Exit - weird" , "Rather unusual" , "escape route" , "Exit - eccentric" , "Hit wicket, for example" .)