Line used in popular culture (3)
I believe the answer is:
arc
'line' is the definition.
(I know that arc is a type of curve)
'in popular culture' is the wordplay.
'in' indicates a hidden word.
'ARC' is hidden in the letters of 'popular culture'.
'used' is the link.
(Other definitions for arc that I've seen before include "Don't go straight" , "Segment of circle" , "Part of a curve" , "section of Circle Line" , "Bow" .)