Rider's foot support (7)
I believe the answer is:
stirrup
'rider's foot support' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for stirrup that I've seen before include "Small bone of the middle ear - it purrs (anag)" , "one puts the boot into" , "This helps one to hear" , "Rider's footpiece" , "Rider's foot support" .)