Reason to have minced (6)
I believe the answer is:
ground
I believe this clue is a double definition.
'reason' is the first definition.
(I know that reason can be written as ground)
'minced' is the second definition.
(I've seen this before)
'to have' is the link.
(Other definitions for ground that I've seen before include "broken into small particles" , "Earth; crushed to powder" , "Terrain" , "Arena" , "Bring down" .)