Lunar feature cold? Very much not hot (6)
I believe the answer is:
crater
'lunar feature' is the definition.
(the moon has many craters)
'cold? very much not hot' is the wordplay.
'cold?' becomes 'c' (eg on taps).
'very much' becomes 'rather'.
'not' suggests deleting specific letters.
'hot' becomes 'h' (abbreviation eg on taps).
'rather' with 'h' removed is 'rater'.
'c'+'rater'='CRATER'
(Other definitions for crater that I've seen before include "Pit resulting from impact or explosion" , "Volcanic depression" , "Bowl-shaped cavity, in a volcano say" , "Hole left by explosion" , "Volcanic cavity" .)