Eight-legged creature (8)
'eight-legged creature' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for spider that I've seen before include "Prised out the insect" , "A common arachnid" , "Insect-eater" , "Arthropod; snooker rest" , "Snooker-cue rest" .)
(Other definitions for arachnid that I've seen before include "Harvestman, possibly," , "Class of animal including spiders and scorpions" , "Incy Wincy Spider, say" , "Spider or scorpion for example" , "Spider, mite, tick etc.; had in car (anag.)" .)