The plane in flight, a jumbo (8)
I believe the answer is:
elephant
'a jumbo' is the definition.
(Jumbo was an elephant who lived in London Zoo)
'the plane in flight' is the wordplay.
'in flight' indicates anagramming the letters (the letters fly around).
'the'+'plane'='theplane'
'theplane' is an anagram of 'ELEPHANT'.
(Other definitions for elephant that I've seen before include "Trunk on one" , "Trunk carrier?" , "Tusked mammal" , "The animal that never forgets" , "Get this animal from Pat and Helen" .)