More frivolous arsonist? (7)
I believe the answer is:
lighter
'more frivolous arsonist?' is the definition.
'lighter' can be an answer for 'arsonist?'. I'm not sure about the 'more frivolous' bit.
'frivolous arsonist?' is the wordplay.
'frivolous' becomes 'light' (light can mean trivial or unimportant).
'arsonist?' becomes 'er' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'light'+'er'='LIGHTER'
Can you help me to learn more?
(Other definitions for lighter that I've seen before include "that leads the way for others?" , "Fire-raiser" , "carrying less cargo?" , "Ship to shore boat" , "more blonde" .)