Boat steerer loses its first milk provider (5)

I believe the answer is:

udder

I'm a little stuck... Click here to teach me more about this clue!

'milk provider' is the definition.
(I've seen this in another clue)

I don't understand the remainder of the clue.

(Other definitions for udder that I've seen before include "Animal mammary gland" , "Animal organ with more than one teat" , "milk supplier" , "Milk supply" , "Bovine mammary gland" .)

I've seen this clue in the Sydney Morning Herald.

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.