East Ender's stray baby cat (5)
I believe the answer is:
tabby
'cat' is the definition.
(I know that tabby is a type of cat)
'east ender's stray baby' is the wordplay.
'ender' says to take the final letters (I've seen 'end' mean this).
'stray' indicates anagramming the letters.
The last letter of 'east' is 't'.
'baby' anagrammed gives 'abby'.
't'+'abby'='TABBY'
(Other definitions for tabby that I've seen before include "Brindled cat" , "Cat with grey or brown streaks or patches" , "Grey-brown cat" , "Streaked cat" , "Mottled and striped grey or brownish cat" .)