An accident to make light of (5)
I believe the answer is:
spill
This could be a double definition.
'an accident' is the first definition.
(I've seen this before)
'light of' is the second definition.
'spill' can be an answer for 'light' (I've seen this before). I am unsure of the 'of' bit.
'to make' is the link.
Can you help me to learn more?
(Other definitions for spill that I've seen before include "Allow to drop - fire lighter" , "Cause liquid to overflow" , "Cause to fall from horse" , "Accidentally cause to overflow" , "Cause liquid to flow from a container" .)