New aim - leave as a friend (5)
I believe the answer is:
amigo
'a friend' is the definition.
('friend' in Spanish)
'new aim leave' is the wordplay.
'new' is an anagram indicator.
'leave' becomes 'go' (to go is to depart or leave).
'aim' anagrammed gives 'ami'.
'ami'+'go'='AMIGO'
'as' acts as a link.
(Other definitions for amigo that I've seen before include "A Mexican pal" , "Quixote's friend" , "Pal from Madrid?" , "friend from Barcelona" , "Spanish word meaning friend" .)