Peacekeepers usher journalist to fuel (8)
I believe the answer is:
unleaded
'fuel' is the definition.
(I have seen 'Such fuel' mean 'unleaded' so perhaps 'fuel' could also mean 'unleaded')
'peacekeepers usher journalist' is the wordplay.
'peacekeepers' becomes 'un'.
'usher journalist' becomes 'leaded' (I can't explain this - if you can you should give a lot more credence to this answer).
'un'+'leaded'='UNLEADED'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for unleaded that I've seen before include "Petrol containing no harmful compounds" , "cleaner fuel" , "Commonly-used petrol without harmful chemical" , "Kind of petrol" , "Describes petrol with toxic metallic element removed" .)