Figures no cats go astray (8)
I believe the answer is:
octagons
'figures' is the definition.
(octagon is a kind of figure)
'no cats go astray' is the wordplay.
'astray' indicates an anagram.
'no'+'cats'+'go'='nocatsgo'
'nocatsgo' is an anagram of 'OCTAGONS'.
(Other definitions for octagons that I've seen before include "Geometric figures with eight sides" , "Eight-sided geometric figures" , "Eight-sided shapes" .)