A is for... Accompanist

Also antique music stand, ankles crossed, arms akimbo and 'avin' a bit of a loaf in an armchair adjacent the attic stairs, while the choir does an a cappella air.
And amusedly anticipating all the applause in an atmosphere of aural ambience - accurately assuming an all-approving audience actually assembles in April.
And alliteration.
Alright?

(I think this might be a tiny bit late to catch the first week of this alleged challenge, but I don't actually give a rat's arse. 'Avin a go anyway. It's still Sunday in America, Argentina, the Aleutians...)