Boy without desire needs medic (7)
I believe the answer is:
surgeon
'medic' is the definition.
(I've seen this before)
'boy without desire' is the wordplay.
'boy' becomes 'son' (synonyms).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'desire' becomes 'urge' (I've seen this in other clues).
'son' placed around 'urge' is 'SURGEON'.
'needs' acts as a link.
(Other definitions for surgeon that I've seen before include "9 practitioner (through keyhole?)" , "Hospital worker" , "Medical man" , "incisive person" , "Physician" .)