So, America on Thursday? (4)
I believe the answer is:
thus
'so' is the definition.
(I know that so can be written as thus)
'america on thursday?' is the wordplay.
'america' becomes 'US' (United States).
'on' means one lot of letters go next to another.
'thursday?' becomes 'Th' (common abbreviation).
'us' put after 'th' is 'THUS'.
(Other definitions for thus that I've seen before include "Like so" , "As a result" , "'So, therefore (4)'" , "as indicated" , "an original Christmas gift" .)