lone
A four-letter word that means "only" or "single" is "sole." It can refer to being the only one of something or to indicate uniqueness.
area
made is a 4 letter word. -.-" I don't mean to sound rude, but, made is a four letter word and the only four letter word with the four letter word 'MADE' in it is made.
Mast(like on a ship) can become mask
Newt
Core.
The only word I can think of would be show.
away area, ants, afar......theres lots!
open
skin
AjarAjeethose are the only ones i could find.
ante, ant, an, a