Possible Clues:

• Misguidedly train as practitioner of 12
• Journeyman taking sides, though not at first
• Potter or jeweler, e.g
• Sinatra seen to be exceptional craftsman
• Sitting in dustcart is 'ancillary skilled worker'
• Tart is a nuisance embracing mechanic
• Craftsman in part is a novice
• Skilled worker is cutting cloth, short of time
• Is in the middle of art and an expert worker
• Skill is a necessity principally for mechanic