Runs away from invertebrates, they say (5)
I believe the answer is:
flees
'runs away' is the definition.
(I've seen this before)
'invertebrates they say' is the wordplay.
'invertebrates' becomes 'fleas' (flea is a kind of invertebrate).
'they say' shows a homophone (sound like).
'fleas' is a homophone of 'FLEES'.
'from' is the link.
(Other definitions for flees that I've seen before include "flies" , "Runs away" .)