Upsets the lighters (6)
I believe the answer is:
spills
'lighters' is the definition.
The definition and answer can be both man-made objects as well as being plural nouns.
Perhaps there's an association between them I don't understand?
'upsets' is the wordplay.
I cannot quite understand how this works, but
'upsets' could be 'ills' (ill is a kind of upset) and 'ills' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'the' acts as a link.
Can you help me to learn more?
(Other definitions for spills that I've seen before include "Pieces of rolled paper used to light a fire" , "Causes liquid to flow out" , "Pieces of rolled paper used to light fires" .)