Thought middleman oddly ignored (4)
I believe the answer is:
idea
'thought' is the definition.
(idea is a kind of thought)
'middleman oddly ignored' is the wordplay.
'oddly ignored' indicates alternate letters (letters in odd-numbered positions removed).
The alternating letters of 'middleman' are 'IDEA'.
(Other definitions for idea that I've seen before include "Plato's Form is" , "Content of cognition" , "Product of the mind" , "Intention" , "Clue" .)