A pistol Ruby returned clipped off finger tip when held by radical (9)
I believe the answer is:
derringer
'a pistol' is the definition.
(derringer is a kind of pistol)
'ruby returned clipped off finger tip when held by radical' is the wordplay.
I cannot quite understand how this works, but
'off' could be 'erring' (I've seen this in another clue) and 'erring' is located in the answer.
'when' could be 'e' (I've seen this in other clues) and 'e' is found within the answer.
'radical' could be 'r' (chemistry abbreviation) and 'r' is found in the answer.
A single letter 'd' remains which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for derringer that I've seen before include "Weapon" , "Pocket pistol" , "Small pistol used by gamblers in western films" , "Short-barrelled American pistol" .)