Singer, one in debt, rated poorly (7,3)
I believe the answer is:
bearded tit
'singer' is the definition.
(I've seen this before)
'one in debt rated poorly' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in' is an insertion indicator.
'poorly' indicates anagramming the letters.
'debt'+'rated'='debtrated'
'debtrated' is an anagram of 'beardedtt'.
'i' placed inside 'beardedtt' is 'BEARDED TIT'.
(Other definitions for bearded tit that I've seen before include "Small songbird, also called the reedling" , "Singer" , "Conchita Wurst to her critics?" .)