Vehicle that's infested? (5)
I believe the answer is:
buggy
I believe this clue is a double definition.
'vehicle' is the first definition.
(buggy is a kind of vehicle)
'that's infested?' is the second definition.
(infested with bugs)
(Other definitions for buggy that I've seen before include "A small vehicle as for baby" , "Of software, containing errors" , "Pushchair - small motorised vehicle" , "Open-topped vehicle" , "Light horse-drawn vehicle; infested" .)