Accordingly, American follows half of them (4)
I believe the answer is:
thus
'accordingly' is the definition.
(I've seen this in other clues)
'american follows half of them' is the wordplay.
'american' becomes 'us' (abbreviation for United States).
'follows' is a charade indicator (letters next to each other).
'half of' indicates taking half.
'them' halved is 'th'.
'us' after 'th' is 'THUS'.
(Other definitions for thus that I've seen before include "Therefore, hence" , "In this way" , "It follows" , "Consequently" , "as indicated" .)