I test duet out - it's poor (9)
I believe the answer is:
destitute
'poor' is the definition.
('destitute' can be similar in meaning to 'poor')
'i test duet out' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'i'+'test'+'duet'='itestduet'
'itestduet' with letters rearranged gives 'DESTITUTE'.
'it's' acts as a link.
(Other definitions for destitute that I've seen before include "In utter want" , "Impoverished, indigent" , "Absolutely broke, without money or goods" , "Poverty-stricken" , "Without money or resources" .)