Spiny anteater can hide in ruins (7)
I believe the answer is:
echidna
'spiny anteater' is the definition.
(synonyms)
'can hide in ruins' is the wordplay.
'in ruins' indicates anagramming the letters.
'can'+'hide'='canhide'
'canhide' is an anagram of 'ECHIDNA'.
(Other definitions for echidna that I've seen before include "Australian creature" , "Creature with spines" , "This insectivore" , "Insectivorous mammal" , "One preying on the workers" .)