Disputed the necessity for carrying a gun (7)
I believe the answer is:
negated
'disputed' is the definition.
(thesaurus)
'the necessity for carrying a gun' is the wordplay.
'the necessity for' becomes 'need' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'carrying' indicates putting letters inside.
'a gun' becomes 'gat' (gat is a kind of gun).
'need' placed around 'gat' is 'NEGATED'.
Can you help me to learn more?
(Other definitions for negated that I've seen before include "Nullified" , "Contradicted" , "Abrogated" , "Cancelled or destroyed the effect of something" , "Made ineffective" .)