Afternoon nap (6)
I believe the answer is:
siesta
'afternoon nap' is the definition.
(Spanish term for an afternoon nap)
This is all the clue.
(Other definitions for siesta that I've seen before include "After lunch nap" , "A Spanish mid-day nap" , "Afternoon nap in Cadiz" , "Afternoon sleep" , "Rest of Spain" .)