Thoughtful and dear partner no longer leaves (7)
I believe the answer is:
pensive
'thoughtful' is the definition.
(similar in meaning)
'dear partner no longer leaves' is the wordplay.
'dear' becomes 'expensive' (similar in meaning).
'partner no longer' becomes 'ex' (I've seen this in other clues).
'leaves' suggests deleting specific letters.
'expensive' with 'ex' taken away is 'PENSIVE'.
'and' is the link.
(Other definitions for pensive that I've seen before include "Brooding" , "Thinking deeply" , "Preoccupied" , "Engaged in deep thought" , "musing" .)