Have regrets about (3)
I believe the answer is:
rue
'have regrets about' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for rue that I've seen before include "Lament; a herb" , "Regret; road (Fr.)" , "Regret in a French street" , "Bitter-tasting herb" , "The 'herb of grace'" .)