Heroic twin brother of princess tormenting us with We Three Kings! Really? (4,9)
I believe the answer is:
luke skywalker
'heroic twin brother of princess' is the definition.
(brother of Princess Leia in Star Wars)
'tormenting us with we three kings really?' is the wordplay.
'three kings' means three replacements for 'king'.
'tormenting' indicates anagramming the letters (I've seen 'tormented' mean this).
'with' means one lot of letters go next to another.
'king' becomes 'K' (abbreviation for king in chess).
'king' becomes 'K' (abbreviation for king in chess).
'king' becomes 'K' (abbreviation for king in chess).
'us'+'we'+'k'+'k'+'k'+'really'='uswekkkreally'
'uswekkkreally' with letters rearranged gives 'LUKE SKYWALKER'.
(Other definitions for luke skywalker that I've seen before include "enemy of Empire" , "Apprentice of Obi-Wan Kenobi" , "Star Wars hero" , "Son of Darth Vader" .)