Spanish composer, excellent, quite the foremost in Andalusia (2,5)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

DEF (excellent) ALL (quite) A (first letter or ‘foremost’ in Andalusia) – we had never heard of this composer, and struggled with the wordplay, trying to figure out how ‘all’ = ‘quite’ – Chambers has it as an adverb equivalent to ‘quite’ or ‘completely’. Our LOI.