After, by and by (5)
I believe the answer is:
later
I believe this is a double definition.
'after' is the first definition.
(I've seen this in another clue)
'by and by' is the second definition.
(synonyms)
(Other definitions for later that I've seen before include "At some time afterwards" , "After a given point in time" , "At a subsequent time" , "more modern" , "Following" .)