Unlock, to a bard (3)
I believe the answer is:
ope
'unlock to a bard' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ope that I've seen before include "Unlock, undo (poetic)" , "Undo, unfold (poetic)" , "moon about, missing maiden" , "Literary form of open" .)