Invention about left Wooster short; big bet coming unstuck -- fool! (15)
I believe the answer is:
flibbertigibbet
'fool' is the definition.
(flibbertigibbet is a kind of fool)
'invention about left wooster short big bet coming unstuck' is the wordplay.
I cannot really see how this works, but
'left' could be 'l' (common abbreviation) and 'l' is located in the answer.
an anagram of 'big' is 'gib' which is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for flibbertigibbet that I've seen before include "Frivolous or flighty person" , "Gossip" , "Flighty type" , "One who's unreliable" , "Till Eulenspiegel, say" .)