Peter for one ruled heartlessly in retrospect (6)
I believe the answer is:
denier
'peter' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe there's a link between them I don't understand?
'one ruled heartlessly in retrospect' is the wordplay.
'one ruled' becomes 'reigned' (I've seen this in another clue).
'heartlessly' says to hollow out the word (remove centre letters).
'in retrospect' says the letters should be written backwards (in retrospect means looking back).
'reigned' with its middle taken out is 'reined'.
'reined' backwards is 'DENIER'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for denier that I've seen before include "Conspiracist probably" , "Units of weight in silks, nylon and other yarns" , "Person refusing to admit (something)" , "Unit of weight for fine material, silk or nylon" , "measure of fine quality" .)