Royal runs off, allegedly (6)
I believe the answer is:
prince
'royal' is the definition.
(prince is a kind of royal)
I cannot understand how the rest of the clue works.
(Other definitions for prince that I've seen before include "eg William or Harry" , "Son of a sovereign" , "Senior male member of a royal family after the sovereign" , "Pincer movement around the royal" , "See 1" .)