EXTRA CHARGE
Credit: LA Times Crossword
Sylvia Bursztyn and Barry Tunick

What do the following words have in common?

ACCORD
STALL
MILL
ACT
PASS
SECT

HINT:
The same three letters will change each word into a new one.

Answers:

Each word can be followed by ION to make a new word:

ACCORDION
STALLION
MILLION
ACTION
PASSION
SECTION