Approve complete oral phase (7)
I believe the answer is:
endorse
'approve' is the definition.
(endorse can mean to approve or support)
'complete oral phase' is the wordplay.
I cannot really see how this works, but
'complete' could be 'do' (doing is a kind of completing) and 'do' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for endorse that I've seen before include "Favour" , "Put one's name to, approve" , "Support (with signature)" , "Affirm" , "Sanction -- red nose (anag)" .)