It's a pleasure to be a doctor (5)
I believe the answer is:
treat
'a doctor' is the definition.
(doctor can mean to give medical treatment)
'it's a pleasure' is the wordplay.
I cannot quite see how this works, but
'a' is within the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found within the answer.
The remaining letters 'ret' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'to be' acts as a link.
Can you help me to learn more?
(Other definitions for treat that I've seen before include "Handle; dainty" , "Alternative to trick" , "Entertain at one's own expense" , "Doctor, manage" , "Behave towards" .)