Device to avoid (5)
I believe the answer is:
dodge
This clue is a double definition.
'device' is the first definition.
(thesaurus)
'avoid' is the second definition.
(dodging is a kind of avoiding)
'to' acts as a link.
(Other definitions for dodge that I've seen before include "Wheeze" , "Western city" , "bypass" , "Move quickly to avoid" , "Elude, sidestep" .)