Idea, however, ending in draft (7)
I believe the answer is:
thought
'idea' is the definition.
('thought' can be a synonym of 'idea')
'however ending in draft' is the wordplay.
'however' becomes 'though' ('though' can be a synonym of 'however').
'ending in' suggests the final letters.
The final letter of 'draft' is 't'.
'though'+'t'='THOUGHT'
(Other definitions for thought that I've seen before include "That's an idea" , "Pensee; consideration" , "Fancy" , "Supposed" , "Meditation" .)