Find out about knight following king (5)
I believe the answer is:
learn
'find out about' is the definition.
(thesaurus)
'knight following king' is the wordplay.
'knight' becomes 'n' (chess).
'following' is a charade indicator (letters next to each other).
'king' becomes 'lear' (I've seen this before).
'n' after 'lear' is 'LEARN'.
(Other definitions for learn that I've seen before include "what pupils do in schools" , "Commit to memory" , "Hear - memorise" , "Study or digest" , "Pick up" .)