Shy, having injured arm in this? (5)
I believe the answer is:
sling
This clue is a double definition.
'shy' is the first definition.
(I've seen this before)
'having injured arm in this?' is the second definition.
(a broken arm may go in a sling)
(Other definitions for sling that I've seen before include "Stone-throwing weapon" , "Cast - used for injured arm" , "ballistic weapon" , "Catapult - shoe - support" , "harness for broken arm" .)