Burial in winter meant WA lost out (9)
I believe the answer is:
interment
'burial' is the definition.
(I know that burial can be written as interment)
'in winter meant wa lost out' is the wordplay.
'in' means one lot of letters goes inside another.
'lost' suggests deleting specific letters.
'out' indicates an anagram (out can mean wrong or inaccurate).
'winter' enclosing 'meant' is 'wintemeantr'.
'wintemeantr' with 'wa' taken away is 'intementr'.
'intementr' anagrammed gives 'INTERMENT'.
(Other definitions for interment that I've seen before include "Burial" , "Procedure governing body" , "planting" .)