Single out cracked Easter egg (9)
I believe the answer is:
segregate
'single out' is the definition.
(I know that segregate is a type of isolate)
'cracked easter egg' is the wordplay.
'cracked' indicates an anagram.
'easter'+'egg'='easteregg'
'easteregg' anagrammed gives 'SEGREGATE'.
(Other definitions for segregate that I've seen before include "Isolate with Easter Egg" , "split" , "Put apart from others for easter egg" , "Quarantine with easter egg" , "Seperate from Easter egg" .)