Pushchair filled with tiny crawlers (5)
I believe the answer is:
buggy
I believe this clue is a double definition.
'pushchair' is the first definition.
(buggy can mean a pram or pushchair)
'filled with tiny crawlers' is the second definition.
(filled with bugs)
(Other definitions for buggy that I've seen before include "A small vehicle as for baby" , "Vehicle for baby, golfer or moon explorer" , "Light horse-drawn vehicle; infested" , "Small open motor vehicle; infested" , "Pushchair - small motorised vehicle" .)