Rev returned to fetch something small and valuable (6)
I believe the answer is:
nugget
'something small and valuable' is the definition.
I can't judge whether this definition defines the answer.
'rev returned to fetch' is the wordplay.
'rev' becomes 'gun' (I've seen this in another clue).
'returned' says the letters should be written in reverse.
'to fetch' becomes 'get' (synonyms).
'gun' in reverse letter order is 'nug'.
'nug'+'get'='NUGGET'
Can you help me to learn more?
(Other definitions for nugget that I've seen before include "Small lump of gold" , "Lump of gold in natural state" , "Piece of gold, information" , "(Small) lump (of value)" , "Get gun to the lump" .)