Bet from elder, say, bringing in 'barrel' (6)
I believe the answer is:
treble
'bet' is the definition.
(I've seen this before)
'elder say bringing in barrel' is the wordplay.
'elder say' becomes 'tree' (elder is a kind of tree).
'bringing in' indicates putting letters inside.
'barrel' becomes 'bl' (I can't explain this - if you can you should believe this answer much more).
'tree' placed around 'bl' is 'TREBLE'.
'from' acts as a link.
Can you help me to learn more?
(Other definitions for treble that I've seen before include "High-frequency (radio control knob)" , "large measure" , "Threefold - singing voice" , "Soprano - multiply by three" , "High boy's singing voice" .)