Doctor puts pressure on cleaner (3)
I believe the answer is:
mop
'pressure on cleaner' is the definition.
'mop' can be an answer for 'cleaner' (something which 'cleans'). I am not sure about the 'pressure on' bit.
'doctor puts' is the wordplay.
'doctor' becomes 'mo' (medical officer).
'puts' becomes 'p' (this might be a standard abbreviation which I don't know about).
'mo'+'p'='MOP'
Can you help me to learn more?
(Other definitions for mop that I've seen before include "Mass of disordered hair" , "Floor cleaner" , "Wet cleaner" , "A thick mass of hair on head" , "Finish off a task - . . . up" .)