Might one wish to warm fingers up in scaling of Mount Sinai, perhaps? (7)
I believe the answer is:
pianist
'might one wish to warm fingers up' is the definition.
(a pianist uses their fingers)
'in scaling of mount sinai perhaps?' is the wordplay.
'scaling of' says the letters should be written backwards (in a down clue, letters go climb up or \'scale\').
'in' indicates a hidden word.
'tsinaip' is hidden in the letters of 'mount sinai perhaps'.
'tsinaip' in reverse letter order is 'PIANIST'.
(Other definitions for pianist that I've seen before include "key man" , "One tickling the ivories" , "Key player" , "Expert on keys" , "Ashkenazy, say" .)