Play wind instrument, perhaps: a dangerous weapon! (8)
I believe the answer is:
blowpipe
'a dangerous weapon' is the definition.
(type of weapon for darts)
'play wind instrument perhaps' is the wordplay.
'play' becomes 'blow' (as in to play an instrument by blowing it).
'wind instrument perhaps' becomes 'pipe'.
'blow'+'pipe'='BLOWPIPE'
(Other definitions for blowpipe that I've seen before include "Through which a poisoned dart is forced" , "Native dart weapon" , "Poison-dart weapon" , "Tube through which poisoned darts are propelled" , "Dart launcher" .)