Bold action - being human in irregular retreat? (7-2)
I believe the answer is:
'bold action' is the definition.
(I've seen this before)
'being human in irregular retreat?' is the wordplay.
'being human' becomes 'erring' (to err is human).
'in' indicates putting letters inside.
'irregular' becomes 'odd'.
'retreat?' says the letters should be written in reverse (I've seen 'retreating' mean this).
'odd' back-to-front is 'ddo'.
'erring' put inside 'ddo' is 'DERRING-DO'.
(Other definitions for derring-do that I've seen before include "Literary word for heroic courage or action" , "Brave and heroic feat(s)" , "Courageous action" , "Daring deeds" , "heroic deeds" .)