Following the plan that previously housed yours and mine (2,6)
I believe the answer is:
on course
'following the plan' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'previously housed yours and mine' is the wordplay.
'previously' becomes 'once' (once means in the past).
'housed' means one lot of letters goes inside another.
'yours and mine' becomes 'ours' (belonging to us).
'once' enclosing 'ours' is 'ON COURSE'.
'that' is the link.
Can you help me to learn more?
(Other definitions for on course that I've seen before include "when receiving instruction?" , "going as expected" , "Enrolled for series of lectures" , "Like betting" , "following set route" .)