26a Somerville and Ross collection ignored Irish (5) T????
23d Odd venue arranged to tackle a little "Nachtmusik" (6) U???E?
27d Matador's first accentless shout (4) ??L?
Thanks bogtrotter. I've heard of The Irish RM - I think it was a tv series a while ago but I couldn't have told you who wrote it. And I never spotted the Mole as one of the measures clues although Ole ran through my mind a few times. And the other is really quite simple now that you've told me the answer - as usual.