Reduced-fat sumo wrestling celebrated (6)
I believe the answer is:
famous
'celebrated' is the definition.
(synonyms)
'reduced-fat sumo wrestling' is the wordplay.
'reduced' means to remove the last letter.
'wrestling' indicates anagramming the letters.
'fat' with its last letter taken off is 'fa'.
'sumo' anagrammed gives 'mous'.
'fa'+'mous'='FAMOUS'
(Other definitions for famous that I've seen before include "Known to very many people" , "Eminent" , "Well known" , "Known and esteemed" , "Known-of widely" .)