Authorises king to enter Cyprus on vacation (6)
I believe the answer is:
clears
'authorises' is the definition.
(I know this)
'king to enter cyprus on vacation' is the wordplay.
'king' becomes 'lear' (King Lear).
'to enter' is an insertion indicator.
'on vacation' means to remove the middle letters.
'cyprus' with its centre taken out is 'cs'.
'lear' placed into 'cs' is 'CLEARS'.
(Other definitions for clears that I've seen before include "Exonerates" , "Empties" .)