You can only change ONE letter, AND/OR rearrange the letters currently available. The first word is:
WINS
easy
base
teas
suet
test
lest
east
sate
team
math
hate
late
tape
spat
salt
lash
shut
hunt
@2610: Uuupppss you changed two letters, but I think it was late in Australia at that time.
And if everybody agrees we go on with:
hash
mash
mush
bush
Sorry.
stub
tube