Old French bread smuggled into Chelsea, perhaps (5)
I believe the answer is:
franc
'old french bread' is the definition.
(I've seen this in another clue)
'smuggled into chelsea perhaps' is the wordplay.
'smuggled' becomes 'ran' (to run something is to smuggle it).
'into' is an insertion indicator.
'chelsea perhaps' becomes 'FC' (short for football club - Chelsea FC is an example).
'ran' inserted into 'fc' is 'FRANC'.
(Other definitions for franc that I've seen before include "European currency until the end of 2001" , "Old French money" , "Former French monetary unit" , "Swiss capital" , "Unit of money" .)