It jumps and is said to run (4)
I believe the answer is:
flea
'it jumps' is the definition.
(fleas are famous for jumping to great heights)
'is said to run' is the wordplay.
'is said' shows a homophone (sound like).
'to run' becomes 'flee' (I've seen this before).
'flee' is a homophone of 'FLEA'.
'and' is the link.
(Other definitions for flea that I've seen before include "high-jumper" , "Member of a circus?" , "Jumping parasite" , "Tiny circus performer?" , "Jumping bloodsucker" .)