Headgear seen on king, on independent island (5)
I believe the answer is:
capri
'island' is the definition.
(Italian island)
'headgear seen on king on independent' is the wordplay.
'headgear' becomes 'cap' (cap is a kind of headgear).
'seen on' is a charade indicator (letters next to each other).
'king' becomes 'R' (abbreviation for rex, king in Latin).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'independent' becomes 'i'.
'cap'+'r'+'i'='CAPRI'
(Other definitions for capri that I've seen before include "Tourist destination" , "Greek island" , "Island in the Gulf of Naples" , "popular resort" , "Romantic Isle in Bay of Naples" .)