You can eat it with port at some stage (6)
I believe the answer is:
orange
'it with port at some stage' is the definition.
The definition suggests a singular noun which matches the answer.
'you can eat' is the wordplay.
'you can' becomes 'o' (I can't justify this - if you can you should give a lot more credence to this answer).
'eat' becomes 'range' (ranging is a kind of eating).
'o'+'range'='ORANGE'
Can you help me to learn more?
(Other definitions for orange that I've seen before include "Belisha beacon colour" , "Unrhymable word?" , "Order colour" , "Go near (anag) - fruit" , "Royal house - fruit - colour" .)