Possible Clues:

• Event a lecturer notes heard in the background
• Score isn't important for what gets played at Croke Park during the summer
• Part of film score, perhaps minus canticle I'd composed
• Background notes including medical units rewritten
• Film score component, and a hint to words hidden in 17-, 27- and 49-Across
• Bars not essential in the theatre?
• Background notes scorers provide for players?
• At home playing Celtic, Man U side almost score
• Moody type in police department goes mental losing head with one of those with rap sheet perhaps
• "Medicinal cuts in" composition