Let's work with ratio suggested by ancient polymath (9)
I believe the answer is:
aristotle
'ancient polymath' is the definition.
'aristotle' can be an answer for 'polymath' (I've seen this before). I'm not sure about the 'ancient' bit.
'let's work with ratio' is the wordplay.
'work with' is an anagram indicator.
'lets' mixed up with 'ratio' can make 'ARISTOTLE'.
'suggested by' is the link.
Can you help me to learn more?
(Other definitions for aristotle that I've seen before include "Philosopher - treats oil (anag)" , "Realist to be like great Greek philosopher" , "Totaliser (anag) - ancient Greek" , "Greek philosopher (Poetics, Politics)" , "Ancient Athenian philosopher, pupil of Plato" .)