Challenging range on satellite over America (9)
I believe the answer is:
ambitious
'challenging' is the definition.
(synonyms)
'range on satellite over america' is the wordplay.
'range on' becomes 'ambit' (synonyms. I am not sure about the 'on' bit.).
'satellite' becomes 'Io' (Io is a moon of Jupiter).
'over' means one lot of letters go next to another (in a down clue, some letters go over others).
'america' becomes 'US' (United States).
'ambit'+'io'+'us'='AMBITIOUS'
(Other definitions for ambitious that I've seen before include "Seeking success" , "Aspirant" , "Bold - pushy" , "Desiring success" , "Intent on achievements" .)