He's imagined to make men go astray (5)
I believe the answer is:
gnome
'he's imagined to' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'men go astray' is the wordplay.
'astray' is an anagram indicator.
'men'+'go'='mengo'
'mengo' with letters rearranged gives 'GNOME'.
'make' acts as a link.
Can you help me to learn more?
(Other definitions for gnome that I've seen before include "statue standing on border?" , "Zurich financier" , "Men go (anag.)" , "Little old elf" , "Mythical sprite" .)