Court official chaired on high (6)
'court official' is the definition.
'umpire' can be an answer for 'official' (I've seen this before). I'm not sure about the 'court' bit.
'chaired on high' is the wordplay.
I cannot quite see how this works, but
'on' could be 're' ('on' can be mean 'with reference to') and 're' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for umpire that I've seen before include "Sports official" , "The ref in cricket match" , "Impartial supervisor" , "Sports arbiter" , "Football official" .)