Cartoon dog without tail trailed by cunning philosopher (8)
I believe the answer is:
plutarch
'philosopher' is the definition.
(ancient Greek philosopher)
'cartoon dog without tail trailed by cunning' is the wordplay.
'cartoon dog' becomes 'pluto' (Disney character).
'without tail' means to remove the last letter.
'trailed by' means one lot of letters go next to another (some letters trail after others).
'cunning' becomes 'arch' (I've seen this before).
'pluto' with its final letter taken away is 'plut'.
'plut'+'arch'='PLUTARCH'
(Other definitions for plutarch that I've seen before include "old biographer" , "ancient historian" , "Classical Greek essayist (Parallel Lives)" , "Ralph cut (anag) - Greek biographer" , "Greek writer" .)