Susie could be the product of the marriage (5)
I believe the answer is:
issue
'product of the marriage' is the definition.
'issue' can be an answer for 'product' (issue is a kind of product). I'm not certain of the 'of the marriage' bit.
'susie could be' is the wordplay.
'could be' is an anagram indicator.
'susie' with letters rearranged gives 'ISSUE'.
'the' is the link.
Can you help me to learn more?
(Other definitions for issue that I've seen before include "Outcome - children" , "Spring - children - publication" , "Matter of dispute" , "Major topic for debate" , "Emanate" .)