Promise of news? (4)
I believe the answer is:
word
This clue is a double definition.
'promise' is the first definition.
(as in 'I give you my word')
'news?' is the second definition.
('word' can be a synonym of 'news')
'of' acts as a link.
(Other definitions for word that I've seen before include "Message" , "Brief statement" , "See 1" , "Statement; signal" , "See 21" .)