The little auk(5)-: R-T-H
A bookmaker(7) : R -N-M-N
Instrument for measuring changes in pressure by variations in electrical conductivity (9): T-S-M-T-R
Cheers...
31a Masonry of uniform blocks in courses of equal height (8) I-O-O-O-
5d Old nickname for Russia based on its cartoon image (8,4) N-R-E-R-/B-A-
THANKS...