One moving slowly to reform Tories (8)
I believe the answer is:
tortoise
'one moving slowly' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'to reform tories' is the wordplay.
'reform' is an anagram indicator (letters in a new form).
'tories' with letters rearranged gives 'rtoise'.
'to'+'rtoise'='TORTOISE'
Can you help me to learn more?
(Other definitions for tortoise that I've seen before include "Lettuce-munching plodder" , "Expected to be slow" , "Mobile home owner?" , "Slow-moving reptile that won race against a hare" , "Land turtle" .)