Current thread of agreement (6)
I believe the answer is:
accord
'agreement' is the definition.
(an accord is a formal agreement)
'current thread' is the wordplay.
'current' becomes 'ac' (alternating current).
'thread' becomes 'cord' (I can't explain this - if you can you should give a lot more credence to this answer).
'ac'+'cord'='ACCORD'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for accord that I've seen before include "Official agreement; harmony" , "Harmony, concurrence" , "Harmonize" , "Model" , "concert" .)