Trainer or sandal, eg (4)
I believe the answer is:
shoe
I believe this clue is a double definition.
'trainer' is the first definition.
(I've seen this before)
'sandal eg' is the second definition.
(sandal is a kind of shoe)
(Other definitions for shoe that I've seen before include "Plate nailed to underside of horse's hoof" , "Flash socket on camera" , "Trainer perhaps" , "Slingback, for example" , "Where a dealer stashes a pack" .)