... King on it makes appearance! (4)
I believe the answer is:
look
'appearance' is the definition.
(I know that look is a type of appearance)
'king on it' is the wordplay.
'king' becomes 'K' (abbreviation for king in chess).
'on' is a charade indicator (letters next to each other).
'it' becomes 'loo' (I am not sure about this - if you are sure you should believe this answer much more).
'k' put after 'loo' is 'LOOK'.
'makes' is the link.
Can you help me to learn more?
(Other definitions for look that I've seen before include "View" , "Inspect" , "Cockney butcher's" , "Behold" , "Search (with the eyes)" .)