King helpfully losing second with regret (8)
I believe the answer is:
ruefully
'with regret' is the definition.
(I've seen this in another clue)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for ruefully that I've seen before include "In a wryly regretful way" , "Loaded with regret" , "Contritely, remorsefully" , "In regretful or doleful way" , "Sorrowfully" .)