Small lump of gold (6)
I believe the answer is:
nugget
'small lump of gold' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for nugget that I've seen before include "Lump of metal like gold" , "Rough lump of gold" , "Piece of precious metal (or chicken?)" , "(Small) lump (of value)" , "Lump sought by the prospector" .)