The stray, after the "Scat!" scampers off (8)
I believe the answer is:
castaway
'the stray' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'the scat scampers off' is the wordplay.
I cannot really see how this works, but
an anagram of 'scat' is 'cast' which is within the answer.
'off' could be 'away' (synonyms) and 'away' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'after' acts as a link.
Can you help me to learn more?
(Other definitions for castaway that I've seen before include ""Captain Bligh"? - with 5d" , "Stranded person" , "Robinson Crusoe was one" , "Type of lace" , "Shipwreck survivor" .)