Protection from light slap or a thrashing (7)
I believe the answer is:
parasol
'protection from light' is the definition.
(I've seen this before)
'slap or a thrashing' is the wordplay.
'thrashing' indicates anagramming the letters (I've seen this in other clues).
'slap'+'or'+'a'='slapora'
'slapora' anagrammed gives 'PARASOL'.
(Other definitions for parasol that I've seen before include "mushroom" , "Sunshade" , ""Sunbrella"" , "cover" , "Desert Shield?" .)