Sounds like something spies used to do at Checkpoint Charlie, as they are not connected (4,6)
I believe the answer is:
Here is my best explanation:
'they are not connected' is the definition.
'sounds like something spies used to do at checkpoint charlie' is the subsidiary indication.
I cannot really see how this works, but
'spies' could be 'agents' (I've seen this before) and 'agents' is present in the answer.
The remaining letters 'free' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'as' is the link.
(Other definitions for free agents that I've seen before include "uncommitted participants" and "people lacking commitment".)