Dad’s time is gone (4)
I believe the answer is:
past
'is gone' is the definition.
(similar in meaning)
'dad's time' is the wordplay.
'dad's' becomes 'pa's' (pa can mean someone's father).
'time' becomes 't' (abbreviation).
'pas'+'t'='PAST'
(Other definitions for past that I've seen before include "historical times" , "Ended" , "Second visitor in 5 [A CHRISTMAS CAROL]" , "Beyond" , "Finished, gone" .)