As a whole pointless, amnesty partially reversed (2,5)
I believe the answer is:
en masse
'as a whole' is the definition.
(I've seen this in another clue)
'pointless amnesty partially reversed' is the wordplay.
'partially' indicates the answer is hidden within the clue.
'reversed' says the letters should be written in reverse.
'essamne' is hidden within 'pointless amnesty'.
'essamne' in reverse letter order is 'EN MASSE'.
(Other definitions for en masse that I've seen before include "in concert" , "In force" , "In a group U altogether" , "All together (Fr.)" , "Many as one" .)