Airmen heading north for miles (3)
I believe the answer is:
far
'airmen heading north for miles' is the definition.
I can't tell whether this definition defines the answer.
'airmen heading north' is the wordplay.
'airmen' becomes 'raf'.
'heading north' says the letters should be written in reverse.
'raf' reversed gives 'FAR'.
Can you help me to learn more?
(Other definitions for far that I've seen before include "A long, long way to go" , "At a great distance way" , "Very much" , "Distant" , "Remote" .)