Opportunity discouraged failure (9)
I believe the answer is:
breakdown
'failure' is the definition.
(I have seen 'Mechanical failure' mean 'breakdown' so perhaps 'failure' could also mean 'breakdown')
'opportunity discouraged' is the wordplay.
'opportunity' becomes 'break' (I have seen 'Better opportunity' mean 'break' so perhaps 'opportunity' could also mean 'break').
'discouraged' becomes 'down' (I've seen this in another clue).
'break'+'down'='BREAKDOWN'
(Other definitions for breakdown that I've seen before include "Collapse - analysis" , "As result of mental stress" , "Detailed analysis" , "Analysis < of separation" , "Mechanical failure" .)