Partly coincide as regards circuit (7)
I believe the answer is:
Here is my best explanation:
'partly coincide' is the definition.
(I've seen this before)
'regards circuit' is the wordplay.
'regards' becomes 'over' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'circuit' becomes 'lap' ('lap' can be a synonym of 'circuit').
'as' acts as a link.
(Other definitions for overlap that I've seen before include "Extend on top of", "Coincide in time or space", "Outflank", "Common area of interest", "Have something in common", "Partly hide", "Put extra cover on", "Imbricate", "Partly cover (another object)" and "Partially cover".)