Knight, for example, has hair cut (3)
I believe the answer is:
man
'knight for example' is the definition.
(knight is a kind of man)
'hair cut' is the wordplay.
'hair' becomes 'mane' (mane is a kind of hair).
'cut' means to remove the last letter.
'mane' with its last letter taken away is 'MAN'.
'has' acts as a link.
(Other definitions for man that I've seen before include "Bloke" , "Geezer" , "Attendant" , "Board token; husband" , "us?" .)