Enthusiasm for gout treatment having succeeded (5)
I believe the answer is:
gusto
'enthusiasm' is the definition.
(I know that gusto is a type of enthusiasm)
'gout treatment having succeeded' is the wordplay.
'treatment' is an anagram indicator (the letters must be processed or treated).
'having' indicates putting letters inside.
'succeeded' becomes 's' (genealogical abbreviation).
'gout' anagrammed gives 'guto'.
'guto' going around 's' is 'GUSTO'.
'for' acts as a link.
(Other definitions for gusto that I've seen before include "Great enjoyment in doing something" , "Great enjoyment, vigour" , "Great relish" , "Hearty enjoyment" , "ardour" .)