Answer: dee

AnswerCrossword Clue
DEEIrish Sea feeder
DEE"Look at Me, I'm Sandra ...!" ("Grease" song)
DEEJust-passing grade
DEERiver in Scotland
DEEJay preceder
DEEWallace of E.T.
DEELetter
DEEJolly Miller's river
DEEAberdeen river
DEERuby in films
DEEThird consonant
DEESnider of Twisted Sister
DEERiver through Wales
DEEBilly .. Williams
DEEDrum head?
DEEOne of the Tweedles
DEELow grade
DEE"Look at Me, I'm Sandra ..." (song from "Grease")
DEERuby of "American Gangster"
DEEHollywood ending?
deehollow electrode for accelerating particles in a cyclotron
DEESlumgullion, e.g.
DEEActress Ruby
DEEActress Wallace-Stone
DEECee follower
DEEDoor opener?
DEEPee .. River
DEEPoor grade
DEEPoor mark
DEERiver to the North Sea
DEEScottish river
DEE"Look at Me, I'm Sandra ..."
DEEWallace of "E.T."
DEE60 or so average
DEEChef Boy-ar-..
DEEGidget portrayer Sandra
DEEReport-card ruiner
DEERuby or Sandra
DEEActress Sandra
DEESandra or Ruby