Criminal held bar as weapon (7)
I believe the answer is:
halberd
'weapon' is the definition.
(halberd is a kind of weapon)
'criminal held bar' is the wordplay.
'criminal' indicates an anagram.
'held'+'bar'='heldbar'
'heldbar' is an anagram of 'HALBERD'.
'as' is the link.
(Other definitions for halberd that I've seen before include "Sharp instrument" , "Combined spear and battleaxe" , "Ancient weapon" , "Old weapon" , "Ancient battle-axe" .)