Describe as being fed up in the East (6)
I believe the answer is:
define
'describe' is the definition.
(thesaurus)
'being fed up in the east' is the wordplay.
'being fed up' becomes 'def' ('fed' going up in a down clue).
'the east' becomes 'e' ('E' can be a synonym of 'east').
'def'+'in'+'e'='DEFINE'
'as' is the link.
(Other definitions for define that I've seen before include "Describe accurately" , "Give exact meaning as of a word" , "Specify" , "Give the meaning or mark the limits of" , "Explain the meaning of a word" .)