Fuss with clues rewritten, about 100 achieving results (10)
I believe the answer is:
successful
'achieving results' is the definition.
I can't judge whether this definition defines the answer.
'fuss with clues rewritten about 100' is the wordplay.
'with' means one lot of letters go next to another.
'rewritten' indicates an anagram.
'about' indicates putting letters inside.
'100' becomes 'C' (Roman numeral).
'fuss' put after 'clues' is 'cluesfuss'.
'cluesfuss' anagrammed gives 'sucessful'.
'sucessful' placed around 'c' is 'SUCCESSFUL'.
Can you help me to learn more?
(Other definitions for successful that I've seen before include "Prosperous" , "achieving aim" , "Winning; flourishing" .)