Answer: slackens

AnswerCrossword Clue
SLACKENSEases off
SLACKENSSlows down.
SLACKENSLets up.
SLACKENSEbbs
SLACKENSLets up
SLACKENSRelaxes
slackensMake or become slack
slackensSLACKEN, to loosen or retard, also SLACK