Act irresponsibly with end of elephant gun (6)
I believe the answer is:
trifle
'act irresponsibly' is the definition.
'trifle' can be an answer for 'act' (trifling is a kind of acting). I am not certain of the 'irresponsibly' bit.
'with end of elephant gun' is the wordplay.
'with' says to put letters next to each other.
'end of' says to take the final letters.
'gun' becomes 'rifle' (rifle is a kind of gun).
The final letter of 'elephant' is 't'.
't' next to 'rifle' is 'TRIFLE'.
Can you help me to learn more?
(Other definitions for trifle that I've seen before include "Possible component of meal" , "A desert of no importance" , "A bit" , "Filter (anag.)" , "Mess" .)