Sinful use of a gun, oddly mentioned (7)
I believe the answer is:
ungodly
'sinful' is the definition.
(I know that sinful can be written as ungodly)
'use of a gun oddly mentioned' is the wordplay.
I cannot really see how this works, but
'of' could be 'o' and 'o' is found within the answer.
an anagram of 'gun' is 'ung' which is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ungodly that I've seen before include "being so early?" , "Characterised by iniquity" , "Ugly Don being irreligious" , "Irreligious, immoral" , "Outrageous; sinful" .)