Area coldest, close against part of leg (8,6)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

A[rea], CHILL[i]EST, END (close) ON (against]. Is chillest a word meaning coldest, or if it’s more correctly chilliest, how does the i disappear? Or is it a verb form, I chill, thou chillest, he chills? But cold isn’t a verb, is it.