Container, as required by brass band members (5)
I believe the answer is:
tubas
'band members' is the definition.
(I've seen this in another clue)
'container as required by' is the wordplay.
'container' becomes 'tub' (tub is a kind of container).
'required by' says to put letters next to each other.
'tub'+'as'='TUBAS'
'brass' is the link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for tubas that I've seen before include "What some musicians" , "Large brass instruments" .)