Friend in a fighter plane heading for Omsk (5)
I believe the answer is:
amigo
'friend' is the definition.
(thesaurus)
'a fighter plane heading for omsk' is the wordplay.
'fighter plane' becomes 'mig'.
'heading for' suggests taking the first letters.
The first letter of 'omsk' is 'o'.
'a'+'mig'+'o'='AMIGO'
'in' is the link.
(Other definitions for amigo that I've seen before include "Mexican friend" , "A Spanish pal" , "Friend, comrade" , "Hispanic comrade" , "Foreign ally" .)