Flag up region giving away American land (7)
I believe the answer is:
eritrea
'land' is the definition.
(African country)
'flag up region giving away american' is the wordplay.
'flag' becomes 'tire' (I've seen this before).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'region' becomes 'area' (area is a kind of region).
'giving away' is a deletion indicator.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'tire' back-to-front is 'erit'.
'area' with 'a' taken out is 'rea'.
'erit'+'rea'='ERITREA'
(Other definitions for eritrea that I've seen before include "African country, capital Asmara" , "Country in the Horn of Africa" , "Country to the north of Ethiopia" , "Eire art (anag)" , "It achieved independence from Ethiopia in 1993" .)