Commiserated with mean person (5)
I believe the answer is:
miser
'mean person' is the definition.
(I've seen this before)
'commiserated with' is the wordplay.
'with' says the answer is hidden in the clue.
'MISER' is hidden within 'commiserated'.
(Other definitions for miser that I've seen before include "One such as Scrooge" , "Money-grubber" , "Stingy person like Scrooge" , "Hoarder of money and possessions" , "Tight-fisted person" .)