Check on the French set of data (5)
I believe the answer is:
table
'set of data' is the definition.
'check on the french' is the wordplay.
'check' becomes 'tab' (synonyms).
'on' means one lot of letters go next to another.
'the french' becomes 'le' ('the' in French).
'tab'+'le'='TABLE'
(Other definitions for table that I've seen before include "Food put on this" , "Index" , "League -; dressing -" , "Statistical chart" , "League --; multiplication --" .)