Retreat from all but frightful temperature (7)
I believe the answer is:
hideout
'retreat' is the definition.
(I've seen this before)
'all but frightful temperature' is the wordplay.
'all but' means to remove the last letter ('all but' can mean 'almost' or 'nearly').
'frightful' becomes 'hideous' (I've seen this before).
'temperature' becomes 't' (abbreviation).
'hideous' with its final letter removed is 'hideou'.
'hideou'+'t'='HIDEOUT'
'from' is the link.
(Other definitions for hideout that I've seen before include "sanctuary" , "Place to lie low" , "retreat" , "den" .)