Bag or vessel containing lb1 (6)

I believe the answer is:

valise

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

'bag' is the definition.
(valise is a kind of bag)

I cannot understand how the rest of the clue works.

(Other definitions for valise that I've seen before include "Small piece of luggage" , "Overnight case" , "Elvis A? (anag)" , "Travel bag" , "A small suitcase for Leavis" .)

I've seen this clue in the Evening Standard.

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.