Rubbish is around square (8)
I believe the answer is:
dinosaur
'square' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'rubbish is around' is the wordplay.
'rubbish' indicates anagramming the letters.
'is'+'around'='isaround'
'isaround' is an anagram of 'DINOSAUR'.
Can you help me to learn more?
(Other definitions for dinosaur that I've seen before include "Large extinct reptile" , "Extinct land reptile" , "Extinct monster like Barney, children's TV pal" , "Extinct reptile of enormous size" , "Extinct reptilian animal" .)