One who could put out poster with revised art possibly (10)
I believe the answer is:
advertiser
'one who could put out poster' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'with revised art possibly' is the wordplay.
'with' means one lot of letters go next to another.
'possibly' indicates anagramming the letters.
'revised' put next to 'art' is 'revisedart'.
'revisedart' is an anagram of 'ADVERTISER'.
Can you help me to learn more?
(Other definitions for advertiser that I've seen before include "One publicising a product (S, not Z)" , "One who can use multiple media" , "who does the plugging" , "Commercial producer" , "Part of a newspaper's title" .)