Identify as William (4)
I believe the answer is:
tell
I believe this clue is a double definition.
'identify' is the first definition.
(telling is a kind of identifying)
'william' is the second definition.
(I've seen this in another clue)
'as' is the link.
(Other definitions for tell that I've seen before include "Relate (a story)" , "One who refused to accept tyranny" , "Instruct" , "Make an impact" , "Count - recount" .)