He corrects each misdirected flyer (9)
I believe the answer is:
repairman
'he corrects' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'each misdirected flyer' is the wordplay.
'each' becomes 'per' ('per' can mean for each).
'misdirected' is a reversal indicator (letters go in the wrong direction).
'flyer' becomes 'airman' (synonyms).
'per' backwards is 'rep'.
'rep'+'airman'='REPAIRMAN'
Can you help me to learn more?
(Other definitions for repairman that I've seen before include "Machinery fixer" , "Technician" , "Mr Fix-it" , "An engineer" , "One who makes machines or appliances work again" .)