Level, containing the French football team (6)
I believe the answer is:
eleven
'football team' is the definition.
(I know that football team can be written as eleven)
'level containing the french' is the wordplay.
'level' becomes 'even' (synonyms).
'containing' means one lot of letters goes inside another.
'the french' becomes 'le' ('the' in French).
'even' placed around 'le' is 'ELEVEN'.
(Other definitions for eleven that I've seen before include "Late" , "Number on a side (6)" , "Age to start secondary education" , "Football or cricket team?" , "Number, on a team maybe" .)