Drive, say, almost disappeared (3,2)
I believe the answer is:
egg on
'drive' is the definition.
(thesaurus)
'say almost disappeared' is the wordplay.
'say' becomes 'eg'.
'almost' means to remove the last letter (most of the word but not all of it).
'disappeared' becomes 'gone' (going is a kind of disappearing).
'gone' with its final letter taken off is 'gon'.
'eg'+'gon'='EGG ON'
(Other definitions for egg on that I've seen before include "Prod" , "Soldier may have this" , "this face is obvious embarrassment" , "'Incite, urge (3,2)'" , "Encourage (someone to do a risky thing)" .)