Smaller cut at the front by doctor, one working in theatre (7)
I believe the answer is:
dresser
'one working in theatre' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'smaller cut at the front by doctor' is the wordplay.
I cannot quite see how this works, but
'doctor' could be 'dr' ('Dr' can be a synonym of 'doctor') and 'dr' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for dresser that I've seen before include "another" , "Surgeon's assistant" , "helps actor get ready" , "Theatre worker back-stage" , "Piece of dining-room furniture" .)