Depression in olden times (4)
I believe the answer is:
dent
'depression' is the definition.
(I know that dent is a type of depression)
'in olden times' is the wordplay.
'in' says the answer is hidden in the clue.
'DENT' is hidden in the letters of 'olden times'.
(Other definitions for dent that I've seen before include "Slight hollow" , "'Dinge, depression (4)'" , "Hollow from impact" , "Surface hollow" , "Tend to make small depression" .)