Father’s time is over (4)
I believe the answer is:
past
'over' is the definition.
(I've seen this before)
'father's time' is the wordplay.
'father's' becomes 'pas' (pa is a kind of father).
'time' becomes 't'.
'pas'+'t'='PAST'
'is' acts as a link.
(Other definitions for past that I've seen before include "Finished, gone" , "The time that has elapsed" , "Second visitor in 5 [A CHRISTMAS CAROL]" , "Gone by in time" , "Days gone by" .)