List covering old bird (7)
I believe the answer is:
rooster
'bird' is the definition.
(I know that rooster is a bird)
'list covering old' is the wordplay.
I cannot quite understand how this works, but
'covering' could be 'roost' (roost is a kind of covering) and 'roost' is located in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
(Other definitions for rooster that I've seen before include "Adult male chicken" , "Farmyard cock" , "Adult male domestic fowl" , "Domestic cock" , "Farmyard bird" .)