Extremely poor male quietly stuffing birds (3,4)
I believe the answer is:
the pits
'extremely poor' is the definition.
I can't judge whether this definition defines the answer.
'male quietly stuffing birds' is the wordplay.
'male' becomes 'he' (he refers to a man).
'quietly' becomes 'p' (musical symbol).
'stuffing' means one lot of letters goes inside another.
'birds' becomes 'tits' (tit is a kind of bird).
'he'+'p'='hep'
'hep' put into 'tits' is 'THE PITS'.
Can you help me to learn more?
(Other definitions for the pits that I've seen before include "Absolutely worst person possible" , "A very bad situation (informal)" , "pants" , "place to service a car?" , "place in motor-racing?" .)