Can you hear it turn in the air? (4)
I believe the answer is:
tern
'can you hear it' is the definition.
I can't tell whether this definition defines the answer.
'turn in the air?' is the wordplay.
'turn' becomes 't' (abbreviation in Oxford Dictionary of Abbreviations).
'in the air?' becomes 'ern' (I am not sure about this - if you are sure you should believe this answer much more).
't'+'ern'='TERN'
Can you help me to learn more?
(Other definitions for tern that I've seen before include "Small slender gull" , "Pay rent for seabird" , "Rent out the bird" , "Sea bird, a small gull" , "Seagull" .)