Assassinated US president (7)
(Other definitions for lincoln that I've seen before include "US car marque" , "memorial site for ..." , "American car" , "English cathedral city - US president" , "An assassinated US president" .)
'assassinated us president' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for kennedy that I've seen before include "Catholic US president" , "US president, d. 1963" , "Bay-of-Pigs president" , "US president assassinated in Dallas" , "Nigel -, Br. violinist" .)