Bag or vase containing lb1 (6)
I believe the answer is:
valise
'bag' is the definition.
(I know that valise is a type of overnight bag)
'vase containing lb1' is the wordplay.
'containing' is an insertion indicator.
'lbl' becomes 'li' (I can't explain this - if you can you should give a lot more credence to this answer).
'vase' placed around 'li' is 'VALISE'.
'or' acts as a link.
Can you help me to learn more?
(Other definitions for valise that I've seen before include "Overnight case" , "Small piece of luggage" , "Elvis A? (anag)" , "Travel bag" , "Small travelling bag or suitcase" .)