Large amount brought back by very good shooter (6)
I believe the answer is:
pistol
'shooter' is the definition.
(something which shoots)
'large amount brought back by very good' is the wordplay.
'large amount' becomes 'lot' (a lot of something).
'brought back' says the letters should be written in reverse.
'by' means one lot of letters go next to another.
'very good' becomes 'pis' (I can't explain this - if you can you should give a lot more credence to this answer).
'lot' reversed gives 'tol'.
'tol' after 'pis' is 'PISTOL'.
Can you help me to learn more?
(Other definitions for pistol that I've seen before include "Hand-held firearm" , "Small gun" , "Piece" , "Small firearm" , "Shakespearean - weapon" .)