David's weapon (5)
I believe the answer is:
sling
'david's weapon' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sling that I've seen before include "harness for broken arm" , "Support bandage; drink" , "Chuck; support for damaged arm" , "Arm bandage; hurl" , "attached to a rifle, perhaps" .)