Winter landscape feature melting down first? (9)
I believe the answer is:
snowdrift
'winter landscape feature' is the definition.
'melting down first?' is the wordplay.
'melting' indicates an anagram.
'down'+'first'='downfirst'
'downfirst' with letters rearranged gives 'SNOWDRIFT'.
(Other definitions for snowdrift that I've seen before include "Wintry accumulation" , "Wind-driven winter hazard" , "Midwinter may show one" , "Wintry feature" , "Winter problem" .)