Outspoken victory on coal production (5)
I believe the answer is:
vocal
'outspoken' is the definition.
(I know that outspoken can be written as vocal)
'victory on coal production' is the wordplay.
'victory' becomes 'v' ().
'on' is an insertion indicator.
'production' indicates an anagram.
'coal' is an anagram of 'ocal'.
'v' inserted inside 'ocal' is 'VOCAL'.
(Other definitions for vocal that I've seen before include "Audible in protest" , "Spoken" , "Relating to the human voice" , "Talkative" , "Articulate" .)