Crazy times packing a gun? (5)
I believe the answer is:
barmy
'crazy' is the definition.
(I've seen this before)
'times packing a gun?' is the wordplay.
'times' becomes 'by' (both can mean 'multiplied by').
'packing' means one lot of letters goes inside another (some letters are packed inside).
'a gun?' becomes 'arm' (gun is a kind of arm).
'by' placed around 'arm' is 'BARMY'.
(Other definitions for barmy that I've seen before include "Crackers, daft" , "Mad; crazy" , "-- Army, cricket supporters" , "round the bend" , "Mad (like footballing "army")" .)