He makes one leave the air terminal (4)
I believe the answer is:
igor
'he' is the definition.
'one leave the air terminal' is the wordplay.
'one' becomes 'i' (Roman numeral).
'leave' becomes 'go' (to go is to depart or leave).
'terminal' says to take the final letters (terminal refers to the end).
The final letter of 'air' is 'r'.
'i'+'go'+'r'='IGOR'
'makes' acts as a link.
(Other definitions for igor that I've seen before include "Hero of Borodin" , "Prince of grand opera" , "Stravinsky, perhaps" , "Prince in Borodin's opera" , "Stravinsky, for example" .)