Fearless peacekeepers advanced and became edgy, reportedly ... (8)
I believe the answer is:
unafraid
'fearless' is the definition.
('unafraid' is associated in meaning with 'fearless')
'peacekeepers advanced and became edgy reportedly' is the wordplay.
I cannot really see how this works, but
'peacekeepers' could be 'un' and 'un' is found in the answer.
'advanced' could be 'a' and 'a' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for unafraid that I've seen before include "Not fearful or apprehensive" , "Not cowed" , "Fearless" , "showing no fear" , "game" .)