A great thinker tries a lot to be unconventional (9)
I believe the answer is:
aristotle
'a great thinker' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'tries a lot to be unconventional' is the wordplay.
'to be unconventional' indicates anagramming the letters.
'tries'+'a'+'lot'='triesalot'
'triesalot' with letters rearranged gives 'ARISTOTLE'.
Can you help me to learn more?
(Other definitions for aristotle that I've seen before include "Great Greek philosopher of 4th century B.C." , "Old Greek teacher" , "Totaliser (anag) - ancient Greek" , "Philosopher - treats oil (anag)" , "Greek philosopher, pupil of Plato, tutor of Alexander the Great" .)