Title for Ian McKellen (3)
I believe the answer is:
sir
'title for ian mckellen' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sir that I've seen before include "Title for knight or teacher" , "Feted fellow" , "Knight's title" , "Form of address for a knight" , "Male title of respect" .)