Rubber trees adopted by essentially hawklike bird (7)
I believe the answer is:
kestrel
'bird' is the definition.
(kestrel is a kind of bird)
'rubber trees adopted by essentially hawklike' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'trees' is 'estre' which is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for kestrel that I've seen before include "Small type of falcon" , "Falco tinnuculus" , "Les, trek around the bird" , "High flier" , "High-flyer" .)