Return the shooter and get a lump (6)
I believe the answer is:
nugget
'a lump' is the definition.
(nugget is a kind of lump)
'return the shooter and get' is the wordplay.
'return' shows that the letters should be reversed in order.
'the shooter' becomes 'gun' (I've seen this before).
'and' says to put letters next to each other.
'gun' backwards is 'nug'.
'nug'+'get'='NUGGET'
(Other definitions for nugget that I've seen before include "Solid lump of a precious metal" , "Small amount" , "Lump (of gold, etc)" , "valuable bit of information" , "bit of gold" .)