Group not charged - allowed to leave (3,4)
I believe the answer is:
set free
'charged allowed to leave' is the definition.
I can't judge whether this defines the answer.
'group not' is the wordplay.
'group' becomes 'set' (both can mean a collection).
'not' becomes 'free' (I can't justify this - if you can you should give a lot more credence to this answer).
'set'+'free'='SET FREE'
Can you help me to learn more?
(Other definitions for set free that I've seen before include "Released" , "Turn loose" , "without the box" , "Uncaged birds have been" , "no longer confined" .)