Former times past (6)
I believe the answer is:
bygone
'former' is the definition.
(I've seen this before)
'times past' is the wordplay.
'times' becomes 'by' (both can mean 'multiplied by').
'past' becomes 'gone' (similar in meaning).
'by'+'gone'='BYGONE'
(Other definitions for bygone that I've seen before include "Belonging to the past" , "Erstwhile" , "Of departed days" , "Former - well in the past" , "Gone by (anag.)" .)