Deplore being endlessly cruel (6)

I believe the answer is:

regret

'deplore' is the definition.
(synonyms)

I can't explain the remainder of the clue.

(Other definitions for regret that I've seen before include "Be contrite about" , "Feeling or repentance or sorrow" , "Remorse for something done or left undone" , "Rue - remorse" , "Feel repentance or disappointment" .)

I've seen this clue in The Guardian.

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