Former spouse takes morning assessment (4)
I believe the answer is:
exam
'assessment' is the definition.
'former spouse takes morning' is the wordplay.
'former spouse' becomes 'ex'.
'takes' says to put letters next to each other.
'morning' becomes 'am'.
'ex'+'am'='EXAM'
(Other definitions for exam that I've seen before include "One test" , "One might be taken for English" , "In brief, a test as in school" , "Formal knowledge test" , "Scholastic test" .)