Bond allows criminal to go free - for a while (4)
I believe the answer is:
bail
'bond' is the definition.
(I know that bond can be written as bail)
'criminal to go free for a while' is the wordplay.
I cannot really understand how this works, but
'a' is found in the answer.
The remaining letters 'bil' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'allows' is the link.
Can you help me to learn more?
(Other definitions for bail that I've seen before include "Remove water from -- part of wicket" , "Money paid for temporary release" , "Security for temporary release" , "Security for release from custody" , "Surety - part of wicket - scoop" .)