10a) Falsetto, on the day, endlessly ornamented (8) h?a?n?t? Could this be headnote?
11a) US composer of revolutionary scores, expressing heart (4) ?o?s Could this be Foss?
Hi Lie-in King, you can always be relied upon.
Head tone definitely would seem to be the correct answer but I'm certain of all the letters given (touc(h), Oreg(a)no, Offe(n)bach and egre(t). So Offenbach gives the n for note. Doesn't seem to make sense does it? So perhaps I should go with head note even though your explanation is better.