The same change can be made to each word below to get a new, unrelated word.

1. TAN
2. BRAIN
3. WRING
4. GRAVY
5. REVISED

HINT:
The change involves the same two letters.

Answer:

Each word can be changed into a new one by inserting the letters IT somewhere in the word:

1. TITAN
2. BRITAIN
3. WRITING
4. GRAVITY
5. REVISITED

Credit:
NY Times Crossword
July 5, 1998
Joe DiPietro
DROP IT!