First class choice? (6)
I believe the answer is:
select
'choice?' is the definition.
('select' can be a synonym of 'choice')
'first class' is the wordplay.
'first' becomes 's' (I can't justify this - if you can you should give a lot more credence to this answer).
'class' becomes 'elect' (elect is a kind of class).
's'+'elect'='SELECT'
Can you help me to learn more?
(Other definitions for select that I've seen before include "Choose from several" , "Exclusive - choice" , "Choice, picked out" , "Exclusive, admitting only certain people" , "Choose - choice" .)