Staff ran campaign to keep old currency (5)
I believe the answer is:
franc
'old currency' is the definition.
(I've seen this before)
'staff ran campaign to keep' is the wordplay.
'to keep' indicates the answer is hidden within the clue.
'FRANC' is hidden in the letters of 'staff ran campaign'.
(Other definitions for franc that I've seen before include "money Euro replaced" , "Former French monetary unit" , "Former French currency" , "Foreign capital" , "Historic currency" .)