A Liberal idea, incomplete, however (8)
I believe the answer is:
although
'however' is the definition.
(I've seen this before)
'a liberal idea incomplete' is the wordplay.
'liberal' becomes 'l' (abbreviation).
'idea' becomes 'thought' (synonyms).
'incomplete' means to remove the last letter.
'thought' with its final letter taken off is 'though'.
'a'+'l'+'though'='ALTHOUGH'
(Other definitions for although that I've seen before include "However, but" , "Hugo, halt! (anag)" , "Apart from the fact that" , "Despite the fact that (8)" , "Yet" .)