Straying; knight — (6)
I believe the answer is:
errant
I believe this is a double definition.
'straying' is the first definition.
(I've seen this in another clue)
'knight' is the second definition.
(a knight errant was a medieval wandering knight)
(Other definitions for errant that I've seen before include "Straying from the right course" , "heretical?" , "Quixotic" , "like Don Quixote?" , "so some knights are called" .)