Drop dart (4)
I believe the answer is:
dash
I believe this clue is a double definition.
'drop' is the first definition.
(I've seen this before)
'dart' is the second definition.
(I know that dart can be written as dash)
(Other definitions for dash that I've seen before include "Hurl; rush" , "Run hurriedly; hyphen" , "Dart" , "display of instruments" , "A touch" .)