Platform turned upside-down in watery burn (8)
I believe the answer is:
scaffold
'platform' is the definition.
(I know that scaffold is a type of platform)
'turned upside-down in watery burn' is the wordplay.
'turned' becomes 'off' (synonyms).
'upside down' says the letters should be written backwards.
'in' means one lot of letters goes inside another.
'watery burn' becomes 'scald' (eg scalding with hot water).
'off' written backwards gives 'ffo'.
'ffo' placed into 'scald' is 'SCAFFOLD'.
(Other definitions for scaffold that I've seen before include "1960s group?" , "Framework formerly for executions" , "Platform on which criminals were once hung" , "Temporary erection for workmen - gallows" , "Temporary structure around a building" .)