Warm up inside with a whiskey (4)
I believe the answer is:
thaw
'warm up' is the definition.
(thesaurus)
'inside with a whiskey' is the wordplay.
'inside' says the answer is hidden in the clue.
'THAW' is hidden in the letters of 'with a whiskey'.
(Other definitions for thaw that I've seen before include "De-ice" , "spring weather?" , "(Of ice/snow) melt" , "snow does eventually" , "As Lewis's boss, you'll have seen me" .)