Explained past partner got punched (9)
I believe the answer is:
expounded
'explained' is the definition.
(I've seen this before)
'past partner got punched' is the wordplay.
I cannot quite understand how this works, but
'past' could be 'ex' (similar in meaning) and 'ex' is found in the answer.
'partner' could be 'n' and 'n' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for expounded that I've seen before include "commented on" , "Explained" , "made clear" .)