Enduring within married couple, wild innate embraces (8)
I believe the answer is:
immanent
'enduring within' is the definition.
'married couple wild innate embraces' is the wordplay.
'married' becomes 'm'.
'couple' shows that letters should be duplicated.
'wild' is an anagram indicator.
'embraces' indicates putting letters inside.
'm' doubled is 'mm'.
'innate' anagrammed gives 'ianent'.
'mm' put into 'ianent' is 'IMMANENT'.
(Other definitions for immanent that I've seen before include "(Of God) permanently pervading universe" , "Existing or operating within" , "everywhere in godlike fashion" .)