Answer: sweatit

AnswerCrossword Clue
SWEATITWorry
SWEATITFret
SWEATITBe concerned
SWEATIT"Don't ...!" ("Stay cool!")
SWEATITWorry, slangily
SWEATIT"Don't ...!" ("Chill!")
SWEATITFail to chill
SWEATITBe on tenterhooks
SWEATITBe apprehensive
SWEATITWorry, informally
SWEATITWorry too much