Brass instrument without a container (3)
I believe the answer is:
tub
'container' is the definition.
(tub is a kind of container)
'brass instrument without a' is the wordplay.
'brass instrument' becomes 'tuba' (I've seen this before).
'without' is a deletion indicator.
'tuba' with 'a' taken away is 'TUB'.
(Other definitions for tub that I've seen before include "'Broad, open vessel (3)'" , "An informal bath or boat" , "Bath; leaky ship" , "old boat?" , "Slow boat; box of ice-cream" .)