Wander out of terror (3)
I believe the answer is:
'wander' is the definition.
(to err is to go astray)
'out of terror' is the wordplay.
'out of' indicates a hidden word.
'ERR' is hidden in the letters of 'terror'.
(Other definitions for err that I've seen before include "Go astray" , "Bungle" , "Stray from the straight and narrow" , "have an affair?" , "Slip up" .)