Possible Clues:

• Mental pictures - I am grey (anag)
• How I claim to be a grey sort of twist in a figurative manner
• I'm a long time with lines, making pictures
• Pictures grimy, each not half in need of restoration
• Pictures one may hold up say, right?
• Single lines encompassing wise man's metaphors, for example
• Picture railway in poetic description
• A heartless chap supporting the writer's figures of speech
• Feature of good poetry
• I am one getting older and unknown paintings