Prince on edge around a king (5)
I believe the answer is:
priam
'king' is the definition.
(I've seen this before)
'prince on edge around a' is the wordplay.
'prince' becomes 'p' (abbreviation).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'edge' becomes 'rim' (rim is a kind of edge).
'around' means one lot of letters goes inside another.
'rim' going around 'a' is 'riam'.
'p'+'riam'='PRIAM'
(Other definitions for priam that I've seen before include "The last king of Troy, in Greek mythology" , "Father of Paris in Troy" , "Old king" , "Trojan king" , "Ruler of Troy" .)