Field of expertise in The Far East (4)
I believe the answer is:
area
'field of expertise' is the definition.
(I've seen this in another clue)
'in the far east' is the wordplay.
'in' indicates a hidden word.
'AREA' is hidden in the letters of 'far east'.
(Other definitions for area that I've seen before include "Part of a building, city etc" , "Expanse of a surface" , "Speaking formally to (someone)" , "part of town" , "Region, zone" .)