Source of a low blow? (4)
I believe the answer is:
tuba
(Other definitions for tuba that I've seen before include "horn" , "Noisy instrument" , "blow it!" , "part of 14 [ORCHESTRA] ?" , "music-maker" .)
I believe the answer is:
tuba
(Other definitions for tuba that I've seen before include "horn" , "Noisy instrument" , "blow it!" , "part of 14 [ORCHESTRA] ?" , "music-maker" .)