Big bass brass (4)

I believe the answer is:

tuba

(Other definitions for tuba that I've seen before include "Brass band instrument" , "blow it!" , "Brass instrument of low pitch" , "Brassy thing" , "A bass instrument" .)

I've seen this clue in the Universal.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.