Bergerac keeps time (3)
I believe the answer is:
era
'time' is the definition.
(era is a kind of time)
'bergerac keeps' is the wordplay.
'keeps' says the answer is hidden in the clue.
'ERA' can be found hidden inside 'bergerac'.
(Other definitions for era that I've seen before include "Special time" , "Long historic period" , "A particular period of time" , "Long stretch" , "Cycle" .)