One having trunk in the plane possibly (8)
I believe the answer is:
elephant
'one having trunk' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'the plane possibly' is the wordplay.
'possibly' is an anagram indicator.
'the'+'plane'='theplane'
'theplane' anagrammed gives 'ELEPHANT'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for elephant that I've seen before include "Large animal (in the room?)" , "Trumpeter" , "Large land mammal" , "Then leap (anag.)" , "Largest land mammal" .)