Where one may serve royal assembly (5)
I believe the answer is:
court
'assembly' is the definition.
(I know that court is a type of court)
'where one may serve royal' is the wordplay.
I cannot really see how this works, but
'one' could be 'o' (I've seen this in other clues) and 'o' is located in the answer.
'royal' could be 'r' (abbreviation) and 'r' is found in the answer.
The remaining letters 'cut' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for court that I've seen before include "Woo; tribunal" , "SECOND PART OF 5" , "Foolishly invite" , "Hall of justice" , "Pay suit to, woo" .)