Mount from Newmarket, napped (4)
I believe the answer is:
etna
'mount' is the definition.
(Etna is an example)
'from newmarket napped' is the wordplay.
'from' indicates the answer is hidden within the clue.
'ETNA' is hidden within 'newmarket napped'.
(Other definitions for etna that I've seen before include "Europe's highest active volcano" , "It sometimes blows its top" , "Volcano in Italy" , "Dangerous peak" , "Natural hazard" .)