Hint: There are 5 words on the left side of the grid that if you add the same word to, they make sense. Likewise for 5 words on the right side of the grid.
Reveal: There are 5 WILLS in the grid that are in the same rows as 5 WAYS: 1ASMITH (Will) and 6AMILKY (way), 15AARNETT (Will) and 16APARK (way), 26AFORTE (Will) and 28AHARMS (way), 42AGOOD (will) and 44AAPPIAN (way), 51APOWER (will) and 52ABROAD (way). Hence the proverb "Where there's a will, there's a way."
I got WAY first, which made it hard because all the WAYs are suffixes, which made me look for a consistent prefix for the left side. ARNETT got it for me, oddly enough.