Shakespearean king with new master (5)
I believe the answer is:
learn
'master' is the definition.
(thesaurus)
'shakespearean king with new' is the wordplay.
'shakespearean king' becomes 'lear' (I've seen this before).
'with' says to put letters next to each other.
'new' becomes 'n'.
'lear'+'n'='LEARN'
(Other definitions for learn that I've seen before include "Succeed in school" , "Read up on" , "Become aware of" , "what pupils do in schools" , "Acquire knowledge or skill" .)