Take possession of old trophy in 100 years (6)
I believe the answer is:
occupy
'take possession' is the definition.
(I've seen this before)
'old trophy in 100 years' is the wordplay.
'old' becomes 'o' (abbreviation).
'trophy' becomes 'cup' (cup is a kind of trophy).
'in' indicates putting letters inside.
'c00' becomes 'C' (Roman numeral).
'years' becomes 'y' (abbreviation).
'c'+'y'='cy'
'cup' placed within 'cy' is 'ccupy'.
'o'+'ccupy'='OCCUPY'
'of' acts as a link.
(Other definitions for occupy that I've seen before include "Employ" , "Inhabit, dwell in" , "Fill, take up (space)" , "Hold (a position) keep (someone) busy" , "Busy - tenant" .)