The attrition of war out East (4)
I believe the answer is:
wear
'the attrition' is the definition.
(thesaurus)
'war out east' is the wordplay.
'out' is an insertion indicator.
'east' becomes 'e' (synonyms).
'war' enclosing 'e' is 'WEAR'.
'of' is the link.
(Other definitions for wear that I've seen before include "Have on - deteriorate from constant use" , "(Put on) clothing" , "Dress in; erode" , "Be clothed in" , "Durability" .)