Light snow covers large crack (5)
I believe the answer is:
split
'crack' is the definition.
(I know that split is a type of crack)
'light snow covers large' is the wordplay.
'light snow' becomes 'spit' (I am not sure about this - if you are sure you should believe this answer much more).
'covers' is an insertion indicator.
'large' becomes 'L' (eg in clothes sizes).
'spit' enclosing 'l' is 'SPLIT'.
Can you help me to learn more?
(Other definitions for split that I've seen before include "Break in pieces - leave" , "Burst open" , "Divorce - Adriatic city" , "shared by a couple?" , "Cleave or divide" .)