Wander out of ferry (3)
I believe the answer is:
err
'wander' is the definition.
(to err is to go astray)
'out of ferry' is the wordplay.
'out of' says the answer is hidden in the clue.
'ERR' is hidden within 'ferry'.
(Other definitions for err that I've seen before include "Boob" , "Blunder" , "Stray from the straight and narrow" , "Go wrong" , "Sin" .)