Fulfilled a large desire after some fiddling (8)
I believe the answer is:
realised
'fulfilled' is the definition.
('fulfilled'->'realized' is in my internal thesaurus and 'ize'->'ise')
'a large desire after some fiddling' is the wordplay.
'a large' becomes 'l'.
'some' says to take the initial letters.
'fiddling' indicates anagramming the letters.
The initial letter of 'after' is 'a'.
'l'+'desire'+'a'='ldesirea'
'ldesirea' with letters rearranged gives 'REALISED'.
(Other definitions for realised that I've seen before include "Understood - cashed in" , "Came to know" , "Fully comprehended" , "Sidereal (anag)" , "Became aware of in sidereal way" .)