Shock about Trump's last letter, perhaps, opening in the style of newsagency (2,7)
I believe the answer is:
al jazeera
'shock about trump's last' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'letter perhaps opening in the style of newsagency' is the wordplay.
I cannot quite understand how this works, but
'letter' could be 'zee' (zee is a kind of letter of the alphabet) and 'zee' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for al jazeera that I've seen is " Channel".)