Answer: EFF

AnswerCrossword Clue
EFFLetter
effeuphemism for fuck
effefficiency
EFFScrabble 4-pointer
EFFFlunker's letter
EFFReport card no-no
EFFGee antecedent
EFFKind of expert: abbr.
EFFStart to fail?
EFFLetter before gee
EFFGrade below dee
EFFWorst grade
EFFIt's heard before "gee"
EFFIn force: Abbr.
EFFValid: Abbr.
EFF"Dang!"
EFFResult: Abbr.
EFFCause's partner: Abbr.
EFFKind of apt.
EFFGee's preceder
EFFValedictorian's nightmare
EFFTerrible grade
EFFYou don't get credit for one
EFFReason for a repeat?
EFFFresh start?
EFFSmall apt.
EFFGee preceder
EFFFalse start?
EFFCapital of France?
EFFBeg. date