A French team playing in Madrid? Amazing! (6)
I believe the answer is:
unreal
'amazing' is the definition.
(unreal can informally mean amazing or incredible)
'a french team' is the wordplay.
'a french' becomes 'un' ('a' in French).
'team' becomes 'real' (Real Madrid).
'un'+'real'='UNREAL'
'playing in madrid?' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for unreal that I've seen before include "Lacking in substance" , "fake" , "Not true to life" , "Dreamlike" , "Phantasmagorical" .)