Oft holler 'Thief!' mischievously, just to have a laugh (3,3,4,2,2)
I believe the answer is:
for the hell of it
'to have a laugh' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'oft holler thief mischievously' is the wordplay.
'mischievously' is an anagram indicator (I've seen this in other clues).
'oft'+'holler'+'thief'='ofthollerthief'
'ofthollerthief' is an anagram of 'FOR THE HELL OF IT'.
'just' acts as a link.
Can you help me to learn more?
(Another definition for for the hell of it that I've seen is " pursuing fun".)