She took the silver coin back (5)
I believe the answer is:
agnes
'she' is the definition.
'silver coin back' is the wordplay.
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'coin' becomes 'sen' (I have seen 'Japanese coin ' mean 'sen' so perhaps 'coin' could also mean 'sen').
'back' says the letters should be written in reverse.
'sen' in reverse letter order is 'nes'.
'ag'+'nes'='AGNES'
'took the' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for agnes that I've seen before include "girl" , "Tube for cables" , "Patron saint of virgins" , "Lady" , "Miss Grey" .)