Time in therapy (3)
I believe the answer is:
era
'time' is the definition.
(I know that era is a type of geologic time)
'in therapy' is the wordplay.
'in' says the answer is hidden in the clue.
'ERA' is hidden within 'therapy'.
(Other definitions for era that I've seen before include "Specific time" , "8" , "Geological age" , "generation, maybe" , "Long period of time" .)