European runner wearing short suit and casual footwear (10)
I believe the answer is:
espadrille
'casual footwear' is the definition.
'espadrille' can be an answer for 'footwear' (espadrille is a kind of footwear). I'm not sure about the 'casual' bit.
'european runner wearing short suit' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'runner' becomes 'r' (abbreviation).
'wearing' indicates putting letters inside.
'short suit' becomes 'spadille' (I am not sure about this - if you are sure you should believe this answer much more).
'r' placed into 'spadille' is 'spadrille'.
'e'+'spadrille'='ESPADRILLE'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for espadrille that I've seen before include "Light rope-soled shoe" , "[SHOE], made casually" , "Cord-soled shoe" , "Plaited fibres in its sole" , "sandal!" .)