Head back with close friend in America, showing easy good nature (8)
I believe the answer is:
bonhomie
'easy good nature' is the definition.
(I've seen this before)
'head back with close friend in america' is the wordplay.
'head' becomes 'nob' (slang term for the head).
'back' is a reversal indicator.
'with' is a charade indicator (letters next to each other).
'close friend in america' becomes 'homie' (US slang term).
'nob' back-to-front is 'bon'.
'bon'+'homie'='BONHOMIE'
'showing' is the link.
(Other definitions for bonhomie that I've seen before include "Good-natured friendliness" , "Inventory" , "Exuberant friendliness - goodwill" , "genial nature" , "Good fellowship or genial manner in France" .)