Boldness shown by opener very often (5)
I believe the answer is:
nerve
'boldness' is the definition.
(I know that boldness can be written as nerve)
'shown by opener very often' is the wordplay.
'shown by' indicates the answer is hidden within the clue.
'NERVE' is hidden in the letters of 'opener very often'.
(Other definitions for nerve that I've seen before include "Grit" , "Bodily fibre carrying sensation" , "displaying self-possession" , "Bundles of fibres in the body that transmit instructions" , "Mettle, daring" .)