Seven-letter words - change zero to two letters to make a new word (Part 1)

glisten

swinger

singers

zingers

gristle

trifled

deflate

falafel

alfalfa

falloff

flaffer

[OED: var. of flapper, i.e., a bird]

raffled

daffled

defiled

fiddled

defined

fifteen

tensile

scented

coldest