A Labour hero, he is quick to accept Liberal (8)
I believe the answer is:
heracles
'a labour hero' is the definition.
(Hercules or Heracles completed 12 labours)
'he is quick to accept liberal' is the wordplay.
'is quick' becomes 'races' (I am not sure about this - if you are sure you should believe this answer much more).
'to accept' indicates putting letters inside.
'liberal' becomes 'l' (abbreviation).
'races' enclosing 'l' is 'racles'.
'he'+'racles'='HERACLES'
Can you help me to learn more?
(Other definitions for heracles that I've seen before include "Leachers (anag) - Greek hero (who laboured)" , "Mythical labourer" , "hero of superhuman strength" .)