Thus the French are involved in shoe repairs (5)
I believe the answer is:
soles
'repairs' is the definition.
(soling is a kind of repairing)
'thus the french' is the wordplay.
'thus' becomes 'so' (synonyms).
'the french' becomes 'les' (plural form of 'the' in French).
'so'+'les'='SOLES'
'are involved in shoe' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for soles that I've seen before include "Parts of shoes" , "Undersurfaces of feet" , "Fish; bottoms of feet" , "Undersides of feet" , "They're always under one's feet!" .)