Cart infested with insects (5)
I believe the answer is:
buggy
'cart' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for buggy that I've seen before include "Light horse-drawn vehicle; infested" , "Of software, containing errors" , "Pushchair - small motorised vehicle" , "Vehicle for baby, golfer or moon explorer" , "A small vehicle as for baby" .)