1a is FLYTE - FLIGHT.
I'm nearly there. I'm missing 6a and 9d and 7d doesn't seem to make sense:
Wind instrument must be less loud to reveal string one (4)
It seems to me to be (F)LUTE but that doesn't fit with the perimeter saying as I think there should be an O in it.
Also it is misleading to say that what goes round the perimeter is a quotation. It's actually a proverb, albeit a modified one.