Possible Clues:

• Manager's sharp, which is an initial advantage
• What each word in 18-, 20-, 34- and 51-Across could be considered
• Outcome of toss leading to sharp advantage, initially
• Option at toss leads to sharp initial advantage
• Substantial initial advantage
• Teacher's sharp boost
• Early edge
• Publicity for model in middle available if you're quick off the mark
• Reaction to toss-up? Pro gets early advantage
• The nod from principal for a local job