Sad wife hugged by professor (4)
I believe the answer is:
down
'sad' is the definition.
(thesaurus)
'wife hugged by professor' is the wordplay.
'wife' becomes 'w'.
'hugged by' is an insertion indicator (I've seen this in other clues).
'professor' becomes 'don' (I've seen this before).
'w' placed inside 'don' is 'DOWN'.
(Other definitions for down that I've seen before include "Feathers of eider duck" , "when in adversity" , "Soft fine feathers" , "Pillow filler - dejected" , "Out of sorts" .)