Cutter longing to cut into issue (7)
I believe the answer is:
surgeon
'cutter' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'longing to cut into issue' is the wordplay.
'longing' becomes 'urge' (both can mean a desire).
'to cut into' means one lot of letters goes inside another.
'issue' becomes 'son' (issue can mean someone's offspring).
'urge' going within 'son' is 'SURGEON'.
Can you help me to learn more?
(Other definitions for surgeon that I've seen before include "Naval doctor" , "one performing in the theatre" , "Medical knife wielder" , "9 practitioner (through keyhole?)" , "Doctor with cutting tools" .)