Class to speak of disorder (7)
I believe the answer is:
clutter
'disorder' is the definition.
(I know that clutter is a type of disorder)
'class to speak' is the wordplay.
'class' becomes 'cl' (I've seen this in other clues).
'to speak' becomes 'utter' (synonyms).
'cl'+'utter'='CLUTTER'
'of' acts as a link.
(Other definitions for clutter that I've seen before include "Disorderly accumulation" , "Clog up" , "Disorderly mess" , "Untidy mess" , "Confusion" .)