Prayer from common ancestor (3,6)
I believe the answer is:
our father
'prayer' is the definition.
(I've seen this before)
'common ancestor' is the wordplay.
'common' becomes 'our' (I can't justify this - if you can you should give a lot more credence to this answer).
'ancestor' becomes 'father' (father is a kind of ancestor).
'our'+'father'='OUR FATHER'
'from' is the link.
Can you help me to learn more?
(Other definitions for our father that I've seen before include "Early bit of devotion" , "head of family" , "God" , "Lord's Prayer" , "Pater noster" .)