Part-time judge on about arrangement (8)
I believe the answer is:
recorder
'part-time judge' is the definition.
(I've seen this before)
'about arrangement' is the wordplay.
'about' becomes 'rec' (I can't explain this - if you can you should give a lot more credence to this answer).
'arrangement' becomes 'order' (order is a kind of arrangement).
'rec'+'order'='RECORDER'
'on' is the link.
Can you help me to learn more?
(Other definitions for recorder that I've seen before include "A kind of flute or note-taker" , "Registrar" , "sound device" , "Legal officer - wind instrument" , "Annalist" .)