Message divorcee in Times (4)
I believe the answer is:
text
'message' is the definition.
(text message)
'divorcee in times' is the wordplay.
'divorcee' becomes 'ex' (an ex-spouse).
'in' is an insertion indicator.
'times' becomes 'tt' (an abbreviation for time written twice).
'ex' going inside 'tt' is 'TEXT'.
(Other definitions for text that I've seen before include "Words of something printed" , "Mobile phone message" , "Sermon basis" , "Words of a book" , "'Words, not illustrations (4)'" .)