Gun with zero plastic (8)
I believe the answer is:
howitzer
'gun' is the definition.
(howitzer is a kind of gun)
'with zero plastic' is the wordplay.
'plastic' is an anagram indicator (plastic can mean easily moulded).
'with'+'zero'='withzero'
'withzero' is an anagram of 'HOWITZER'.
(Other definitions for howitzer that I've seen before include "High angle gun with a short barrel" , "Trench mortar" , "Military weapon" , "Gun firing shells at a steep angle" , "Cannon with a steep firing angle" .)