Doubled weight in time long ago (7)
I believe the answer is:
twofold
'doubled' is the definition.
(synonyms)
'weight in time long ago' is the wordplay.
'weight' becomes 'w'.
'in' indicates putting letters inside.
'time' becomes 't' (abbreviation).
'long ago' becomes 'ofold' (I've seen this before).
't'+'ofold'='tofold'
'w' going inside 'tofold' is 'TWOFOLD'.
(Other definitions for twofold that I've seen before include "Having dual elements" , "Twice as much" , "Twice as numerous" , "doubled in size" , "Double" .)