Feeble pet cried out (8)
I believe the answer is:
decrepit
'feeble' is the definition.
('decrepit' can be a synonym of 'feeble')
'pet cried out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'pet'+'cried'='petcried'
'petcried' anagrammed gives 'DECREPIT'.
(Other definitions for decrepit that I've seen before include "Enfeebled by age, infirmity" , "rickety" , "Run-down by old age or hard use" , "like a crate?" , "Dilapidated, made weak by age" .)