Like court, or something happening there (6)
I believe the answer is:
atrial
'like court' is the definition.
(like an atrium, court-like space)
'something happening there' is the wordplay.
I cannot really understand how this works, but
'happening' could be 'trial' (trial is a kind of happening) and 'trial' is found in the answer.
A single letter 'a' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
'or' is the link.
(Other definitions for atrial that I've seen before include "Like some courts" , "referring to Chambers?" , "Like main court" , "of the heart cavities" , "Lariat (anag)" .)