Medical care for coniferous trees, thanks to one leading doctor (5,3)
I believe the answer is:
first aid
'medical care' is the definition.
'first aid' can be an answer for 'care' (first aid is a kind of care). I'm unsure of the 'medical' bit.
'coniferous trees thanks to one leading doctor' is the wordplay.
'coniferous trees' becomes 'firs' (fir is a kind of coniferous tree).
'thanks' becomes 'ta' (UK informal version of 'thank you').
'to one' becomes 'i' (Roman numeral).
'leading' indicates taking the first letters (the leading letter of the word).
The initial letter of 'doctor' is 'd'.
'firs'+'ta'+'i'+'d'='FIRST-AID'
'for' is the link.
Can you help me to learn more?
(Other definitions for first aid that I've seen before include "Emergency medical treatment" , "Immediate help for the sick or injured" , "Instant help for the sick" , "Initial treatment for injured person before doctor arrives" , "Immediate assistance to the injured" .)