A site's developed for rest (6)
I believe the answer is:
siesta
'rest' is the definition.
(thesaurus)
'a site's developed' is the wordplay.
'developed' indicates anagramming the letters.
'a'+'sites'='asites'
'asites' is an anagram of 'SIESTA'.
'for' is the link.
(Other definitions for siesta that I've seen before include "Afternoon nap in a warm climate" , "rest of the Spaniards" , "Catnap" , "Diurnal nap in Spain" , "Rest of Spain" .)