Pledge puts meat not oddly into boiled soup (7)
I believe the answer is:
betroth
'pledge' is the definition.
(I know that betroth is a kind of the vow)
'meat not oddly into boiled soup' is the wordplay.
'not oddly' indicates alternate letters (odd letters are removed).
'into' is an insertion indicator.
'boiled soup' becomes 'broth' (broth is a kind of soup. I am not sure about the 'boiled' bit.).
The alternating letters of 'meat' are 'et'.
'et' going into 'broth' is 'BETROTH'.
'puts' is the link.
Can you help me to learn more?
(Other definitions for betroth that I've seen before include "Affiance (one person to another)" , "contract" , "Engage to be married" , "Promise to marry" , "Plight" .)