Sandal making leader slip badly (10)
I believe the answer is:
espadrille
'sandal' is the definition.
(espadrille is a kind of sandal)
'leader slip badly' is the wordplay.
'badly' is an anagram indicator.
'leader'+'slip'='leaderslip'
'leaderslip' is an anagram of 'ESPADRILLE'.
'making' is the link.
(Other definitions for espadrille that I've seen before include "Cord-soled shoe" , "Shoe with a canvas upper" , "goes on foot" , "Plaited fibres in its sole" , "[SHOE], made casually" .)