Tidy vessel to carry king (5,2)
I believe the answer is:
clear up
'tidy' is the definition.
(thesaurus)
'vessel to carry king' is the wordplay.
'vessel' becomes 'cup' (I've seen this in other clues**).
'to carry' is an insertion indicator.
'king' becomes 'lear' (I've seen this before).
'cup' enclosing 'lear' is 'CLEAR-UP'.
(Other definitions for clear up that I've seen before include "how conditions may improve" , "Sort out" , "be less untidy" , "put things in order" , "Tidy; explain; cure" .)