Random opportunity (6)
I believe the answer is:
chance
This clue is a double definition.
'random' is the first definition.
(similar in meaning)
'opportunity' is the second definition.
(synonyms)
(Other definitions for chance that I've seen before include "'Fate, luck, fortune (6)'" , "part of Monopoly" , "Possibility - opportunity" , "Luck or accident" , "Risk doing (something)" .)