Bird eggs delighting beginners shrank (7)
I believe the answer is:
quailed
'shrank' is the definition.
('quail' can be a synonym of 'shrink')
'bird eggs delighting beginners' is the wordplay.
I cannot really understand how this works, but
'bird' could be 'quail' (quail is a kind of bird) and 'quail' is found in the answer.
The remaining letters 'ed' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for quailed that I've seen before include "Flinched" , "Cowered" .)