Prince's loo set up in a cemetery (10)
I believe the answer is:
necropolis
'cemetery' is the definition.
(synonyms)
'prince's loo set' is the wordplay.
'set' indicates anagramming the letters (instruction to set the letters).
'princes'+'loo'='princesloo'
'princesloo' is an anagram of 'NECROPOLIS'.
'up in a' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for necropolis that I've seen before include "Large ancient cemetery" , "burial site" , "Ripon Close (anag) - cemetery" .)