East Ender's stray baby cat (5)
I believe the answer is:
tabby
'cat' is the definition.
(tabby is a kind of cat)
'east ender's stray baby' is the wordplay.
'ender' suggests the final letters (I've seen 'end of' mean this).
'stray' indicates an anagram.
The final 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" .)