6d - Grating sound sound sound (5) ?r?a? I note that previous answers given are either great (sounds like grate) or creak. I would opt for great but who knows?
Someone told me once that it's a nightmare to learn, with different meanings and different pronunciations for the same letter combos (e.g. cough, bough, nought... etc)!
thanks for jogging my old memory, Boxtops. I remember a teacher telling us how foreigners find English hard to learn. He quoted the famous lines ...with a quirky change "Underneath the mistletoe bough (buff)
Stands a boy with a hacking cough (cow)"
I agree with writesbad, and think that the answer is "creak".
You need to split up the clue like this: first find a meaning for "grating sound", which is "creak". The second occurrence of the word "sound" is telling us that "creak" sounds like (or is a homophone for) the one of the meanings of the third occurrence of "sound",
which is "creek".
As a musician, "sound sound sound" and the letters _r_a_ fit TRIAD, a three note chord.
But I guess CREAK is right with this dodgy (copyright Norman Vaughan!!!) clue.