King in robe twirling about (6)
I believe the answer is:
oberon
'king' is the definition.
(I've seen this before)
'robe twirling about' is the wordplay.
'twirling' indicates an anagram.
'about' becomes 'on' ().
'robe' with letters rearranged gives 'ober'.
'ober'+'on'='OBERON'
'in' acts as a link.
(Other definitions for oberon that I've seen before include "...[IN DREAM] with king" , "Shakespeare's fairy king" , "Spirited king" , "King of the fairies (AMND)" , "Borneo (anag)" .)