A warmer nest has to be configured to accommodate ten birds (4,11)
I believe the answer is:
manx shearwaters
'birds' is the definition.
(Manx shearwater is an example)
'a warmer nest has to be configured to accommodate ten' is the wordplay.
I cannot really see how this works, but
'a' could be 'an' and 'an' is located in the answer.
'ten' could be 'x' (Roman numeral) and 'x' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for manx shearwaters that I've seen is " Birds".)