To some extent, at home and not at home (2,1,3)
I believe the answer is:
in a way
'to some extent' is the definition.
(I've seen this before)
'home and not at home' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'and' says to put letters next to each other.
'not at home' becomes 'away' (I've seen this before).
'in'+'away'='IN A WAY'
'at' is the link.
(Other definitions for in a way that I've seen before include "as one might see it" , "Sort of, in some respects" , "In some respects, to a limited extent" , "To some degree" , "From some points of view" .)