Pet getting a stimulant in a stupor (9)
I believe the answer is:
catatonic
'in a stupor' is the definition.
(catatonic can mean in a stupor)
'pet getting a stimulant' is the wordplay.
'pet' becomes 'cat' (I have seen 'Common pet ' mean 'cat' so perhaps 'pet' could also mean 'cat').
'getting' means one lot of letters go next to another.
'stimulant' becomes 'tonic' (I've seen this before).
'cat'+'a'+'tonic'='CATATONIC'
(Other definitions for catatonic that I've seen before include "Rigid and in a stupor through illness" , "Behaving abnormally" , "Insensible" , "In a stupefied state" , "Stupefied and immobile" .)