TASK DEFINITION: You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For consistency, answers should be in all lower cased letters.
PROBLEM: Category: FAMILIAR PHRASES 
Clue: Pool table piece you don't want to be "behind"

SOLUTION: the 8 ball

PROBLEM: Category: BEGINS & ENDS WITH "K" 
Clue: In 1979 this rock group topped the charts with "My Sharona"

SOLUTION: the knack

PROBLEM: Category: DOUBLE Ws 
Clue: One who's recently married

SOLUTION:
a newlywed