Relative from America joining company at home (6)
I believe the answer is:
cousin
'relative' is the definition.
(I know that cousin is a type of relative)
'america joining company at home' is the wordplay.
'america' becomes 'US' (United States).
'joining' is a charade indicator (letters next to each other).
'company' becomes 'co' (abbreviation).
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'us' put after 'co' is 'cous'.
'cous'+'in'='COUSIN'
'from' acts as a link.
(Other definitions for cousin that I've seen before include "Child of one's uncle or aunt" , "Kinsman, generally (archaic)" , "Strange US icon is a relative" , "Aunt/uncle's child" , "person once removed?" .)