Animals prepared to rest (6)
I believe the answer is:
otters
'animals' is the definition.
The answer is an example.
'prepared to rest' is the wordplay.
'prepared' indicates an anagram.
'to'+'rest'='torest'
'torest' is an anagram of 'OTTERS'.
(Other definitions for otters that I've seen before include "Aquatic carnivores" , "web-footed creatures" , "Sleek short-furred swimmers" , "River-dwelling mammals" , "Mammals with webbed feet" .)