Weapon on fire, launched in fight (8)
I believe the answer is:
stiletto
'weapon on fire' is the definition.
'stiletto' can be an answer for 'weapon' (stiletto is a kind of weapon). I'm not sure about the 'on fire' bit.
'launched in fight' is the wordplay.
'launched' becomes 'til' (I can't justify this - if you can you should believe this answer much more).
'in' means one lot of letters goes inside another.
'fight' becomes 'setto' (set-to is a kind of fight).
'til' put inside 'setto' is 'STILETTO'.
Can you help me to learn more?
(Other definitions for stiletto that I've seen before include "One may have a stab" , "Item of footwear" , "Type of shoe" , "Thin blade" , "A short knife, dagger or heel" .)