Convert class after wild rants (9)
I believe the answer is:
transform
'convert' is the definition.
(thesaurus)
'class after wild rants' is the wordplay.
'class' becomes 'form class' (synonyms).
'after' says to put letters next to each other.
'wild' is an anagram indicator.
'rants' anagrammed gives 'trans'.
'form' put after 'trans' is 'TRANSFORM'.
(Other definitions for transform that I've seen before include "adapt" , "Change the voltage I" , "Change completely" , "Change markedly" , "Remodel" .)