One renewed after cuts put an end to by Labour (5)
I believe the answer is:
hydra
'labour' is the definition.
I know that 'labour' relates to this answer. I also know that both the answer and definition are singular nouns
I can't explain the remainder of the clue.
(Other definitions for hydra that I've seen before include "Persistent trouble" , "Mythical nine-headed monster" , "Monster Hercules slew" , "Multi-headed monster killed by Hercules" , "Mythical many-headed snake" .)