Derivates used to plug (9)
I believe the answer is:
advertise
'plug' is the definition.
(thesaurus)
'derivates used' is the wordplay.
'used' is an anagram indicator.
'derivates' anagrammed gives 'ADVERTISE'.
'to' acts as a link.
(Other definitions for advertise that I've seen before include "Give publicity to" , "Publicise, call attention to" , "Publicise, promote" , "Call public attention to" , "Draw attention to, goods for sale perhaps" .)