Superficial American backing France in competition (7)
I believe the answer is:
surface
'superficial' is the definition.
(similar in meaning)
'american backing france in competition' is the wordplay.
'american' becomes 'us' (abbreviation for United States).
'backing' says the letters should be written in reverse.
'france' becomes 'f'.
'in' means one lot of letters goes inside another.
'competition' becomes 'race' (race is a kind of competition).
'us' reversed gives 'su'.
'f' going into 'race' is 'rface'.
'su'+'rface'='SURFACE'
(Other definitions for surface that I've seen before include "Come up for air" , "Outer boundary" , "Outside part" , "Facade" , "Outside layer" .)