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 subsidiary indication.
I cannot quite see how this works, but
'circuit' could be 'lap' ('lap' can be a synonym of 'circuit') and 'lap' is present in the answer.
The remaining letters 'over' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'as' is the link.
(Other definitions for overlap that I've seen before include "Cover and extend beyond", "Imbricate", "Extend on top of", "Rest one on another", "Coincide partly in time", "Partly cover - a plover (anag)", "Partially cover", "Partially coincide", "Partly coincide in time, length etc" and "Lie partly on top of".)