Room 101 all about wet blankets (7)
I believe the answer is:
icecaps
'wet blankets' is the definition.
(blankets of ice or snow)
'room 101 all about' is the wordplay.
'room' becomes 'space' (I've seen this before).
'101' becomes 'ci' (roman numerals).
'all about' says the letters should be written backwards.
'space'+'ci'='spaceci'
'spaceci' in reverse letter order is 'ICECAPS'.
(Other definitions for icecaps that I've seen before include "White sheets" , "objects being eliminated from the world" , "Cold headgear, perhaps?" , "They cover Poles" , "Areas of permanent glaciation" .)