A celebrity on board, right? (4)
I believe the answer is:
star
'a celebrity' is the definition.
(a star is a celebrity or famous person)
'board right?' is the wordplay.
'board' becomes 'st' (I can't justify this - if you can you should give a lot more credence to this answer).
'right?' becomes 'ar' (I've seen this in other clues).
'st'+'ar'='STAR'
'on' is the link.
Can you help me to learn more?
(Other definitions for star that I've seen before include "Hollywood figure" , "Eg, Betelgeuse" , "Sign of a leading performer" , "See 21" , "''Twinkle, twinkle, little ...'' (children's song)" .)