Nine months, verily? (3)
I believe the answer is:
yea
'verily?' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for yea that I've seen before include "Affirmative, colloquially" , "Affirmative vote" , "'She loves you, ... ... ...' (The Beatles)" , "Positive vote" , "Emphatic agreement" .)