Upsets the Spanish blues king on record produced by one of The Stones! (6)
I believe the answer is:
pebble
'one of the stones' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'upsets the spanish blues king on record' is the wordplay.
'upsets' says the letters should be written in reverse.
'the spanish' becomes 'el'.
'blues king on' becomes 'bb' (I can't explain this - if you can you should believe this answer much more).
'record' becomes 'ep'.
'el'+'bb'+'ep'='elbbep'
'elbbep' reversed gives 'PEBBLE'.
'produced by' acts as a link.
Can you help me to learn more?
(Other definitions for pebble that I've seen before include "Small fragment of rock" , "A small smooth stone" , "Little rock" , "Small, round stone" , "Smooth little stone" .)