Needle and what it is (not the head) (5)
I believe the answer is:
arrow
'needle' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
(Other definitions for arrow that I've seen before include "One in a quiver" , "It may indicate" , "Arm" , "What's shot from a bow" , "Missile for bowman" .)