Adoption of America splitting poor Poles (8)
I believe the answer is:
espousal
'adoption' is the definition.
(thesaurus)
'america splitting poor poles' is the wordplay.
'america' becomes 'usa' ('U.S.A.' can be a synonym of 'america').
'splitting' means one lot of letters goes inside another.
'poor' indicates an anagram.
'poles' with letters rearranged gives 'espol'.
'usa' placed within 'espol' is 'ESPOUSAL'.
'of' is the link.
(Other definitions for espousal that I've seen before include "Adoption (of a cause) - USA's pole (anag)" , "old-fashioned marriage" , "Acceptance with approval" , "Adoption, support (of)" , "Action of adopting (a cause)" .)