A partner each and every year (4)
I believe the answer is:
ally
'a partner' is the definition.
(thesaurus)
'each and every year' is the wordplay.
'each and every' becomes 'all' (I've seen this before).
'year' becomes 'y'.
'all'+'y'='ALLY'
(Other definitions for ally that I've seen before include "Team up" , "Friend and colleague" , "Cooperating country" , "Friend in time of need" , "Join by marriage, treaty etc" .)