Cut doctor out in session of enquiry? (5)
I believe the answer is:
quota
'cut' is the definition.
(thesaurus)
'doctor out in session of enquiry?' is the wordplay.
'doctor' indicates anagramming the letters.
'in' means one lot of letters goes inside another.
'session of enquiry?' becomes 'qa' (Q and A, question and answer session).
'out' anagrammed gives 'uot'.
'uot' inserted into 'qa' is 'QUOTA'.
(Other definitions for quota that I've seen before include "Share to which one is entitled" , "amount allowed" , "Proportional share" , "Ration" , "certain allowance" .)