Straggling when infested with arachnids (7)
I believe the answer is:
spidery
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for spidery that I've seen before include "Gangly" , "Like a hand" , "Wispy" , "(Of writing) thin and straggly" , "thin, angular style" .)