Occasionally in the past and present (3,3,4)
I believe the answer is:
now and then
'occasionally' is the definition.
(I've seen this before)
'past and present' is the wordplay.
'past' becomes 'andthen' (I can't explain this - if you can you should believe this answer much more).
'and' means one lot of letters go next to another.
'present' becomes 'now' (both can mean the current period).
'andthen' after 'now' is 'NOW AND THEN'.
'in the' is the link.
Can you help me to learn more?
(Other definitions for now and then that I've seen before include "Sometimes" , "Occasionally" , "making a historical contrast" , "At times" .)