Doubtful after sermon, extremely condescending (6)
I believe the answer is:
sniffy
'condescending' is the definition.
(thesaurus)
'doubtful after sermon extremely' is the wordplay.
'doubtful' becomes 'iffy' (I've seen this before).
'after' says to put letters next to each other.
'extremely' says to hollow out the word (remove centre letters).
'sermon' with its middle removed is 'sn'.
'iffy' after 'sn' is 'SNIFFY'.
(Other definitions for sniffy that I've seen before include "Supercilious; snobby" , "Disdainful" , "Scornful, contemptuous" .)