Here are the possible solutions for diagonal to clue
Answer
Clue
Relevancy
abe
Clue
Nickname of the man (born 2/12/1809) who gave the address at 18A, issued the 28A/45A, was the first elected president of the 60A Party, and whose name can be found in this puzzle's main diagonal
area
Clue
In a rhombus, half the product of its diagonal lengths