Stumble over the French a few times (6)
I believe the answer is:
triple
'a few times' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'stumble over the french' is the wordplay.
'stumble' becomes 'trip' (synonyms).
'over' means one lot of letters go next to another (in a down clue, some letters go over others).
'the french' becomes 'le' ('the' in French).
'trip'+'le'='TRIPLE'
Can you help me to learn more?
(Other definitions for triple that I've seen before include "Three times" , "Multiply by three" , "involving several parties" , "make score sixty?" , "make much longer" .)