In communication a message includes the titles (5)
I believe the answer is:
names
'the titles' is the definition.
(I've seen this in another clue)
'in communication a message includes' is the wordplay.
'in' indicates the answer is hidden within the clue.
'NAMES' is hidden within 'communication a message includes'.
(Other definitions for names that I've seen before include "Some people drop these to sound important" , "Titles" , "People and things are known by them" , "Heroes" , "identification" .)