Former partner with morning paper (4)
I believe the answer is:
exam
'paper' is the definition.
(I've seen this before)
'former partner with morning' is the wordplay.
'former partner' becomes 'ex'.
'with' means one lot of letters go next to another.
'morning' becomes 'am'.
'ex'+'am'='EXAM'
(Other definitions for exam that I've seen before include "Oral maybe" , "Student test" , "End-of-course assessment" , "In brief, a test as in school" , "Test (abbr)" .)