The rest of Spain? (6)
I believe the answer is:
siesta
'the rest of spain' is the definition.
(I've seen this before)
'rest of spain' is the wordplay.
I cannot quite understand how this works, but
'spain' could be 'es' (es is an abbreviation for Spain) and 'es' is found within the answer.
'rest' could be 'sit' (I've seen this in another clue) and 'sit' is found within the remaining letters.
A single letter 'a' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for siesta that I've seen before include "Afternoon sleep" , "Diurnal nap in Spain" , "PM snooze" , "rest of the Spaniards" , "Early afternoon nap" .)