Certain country upset to lose one journalist (7)
I believe the answer is:
assured
'certain' is the definition.
(I've seen this before)
'upset to lose one journalist' is the wordplay.
'upset' shows that the letters should be reversed in order.
'to lose' becomes 'russ' (I can't explain this - if you can you should give a lot more credence to this answer).
'one' becomes 'a'.
'journalist' becomes 'ed' (short for editor).
'russ'+'a'='russa'
'russa' back-to-front is 'assur'.
'assur'+'ed'='ASSURED'
'country' acts as a link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for assured that I've seen before include "Self-confident" , "Confident - certain" , "Secured" , "Exhibiting confidence" , "without doubt" .)