Revealed as hard-hearted in a plot (5)
I believe the answer is:
bared
'revealed' is the definition.
(I've seen this in another clue)
'hard-hearted in a plot' is the wordplay.
'hearted' says to take the centre.
'in' indicates putting letters inside.
'a plot' becomes 'bed' (a plot of land).
The centre of 'hard' is 'ar'.
'ar' going within 'bed' is 'BARED'.
'as' acts as a link.
(Other definitions for bared that I've seen before include "Uncovered" , "Stripped" .)