Pernickety person choosing eggs? (9)
I believe the answer is:
nitpicker
'choosing eggs?' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'pernickety person' is the wordplay.
I cannot quite see how this works, but
'person' could be 'pi' (PI is an example) and 'pi' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for nitpicker that I've seen before include "overcritical fellow" , "critic" , "Particular person" , "Knocker" , "Petty finder of errors" .)