Study of cadences (3)
I believe the answer is:
'study' is the definition.
(term for a study or office)
'of cadences' is the wordplay.
'of' says the answer is hidden in the clue.
'DEN' is hidden in the letters of 'cadences'.
(Other definitions for den that I've seen before include "Wild animal's lair" , "Private office" , "Gentleman's study or animal's lair" , "Animals' shelter" , "Home of the beast" .)