It's a bind for the doctor (8)
I believe the answer is:
ligature
'the doctor' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'it's a bind' is the wordplay.
I cannot quite understand how this works, but
'a' is found in the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
The remaining letters 'ligure' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for ligature that I've seen before include "Musical slur" , "Cord used for tying" , "that flute could begin with" , "Binding used for strangulation" , "Thread used by surgeons" .)