Sponsor's purchase ... or what the starts of 18-, 24-, 51- and 60-Across can have 7 letters

Crossword clues for Sponsor's purchase ... or what the starts of 18-, 24-, 51- and 60-Across can have 7 letters:

AIRTIME: Sponsor's purchase ... or what the starts of 18-, 24-, 51- and 60-Across can have