Insect to escape by the sound of it (4)
I believe the answer is:
flea
'insect' is the definition.
(flea is a kind of insect)
'escape by the sound of it' is the wordplay.
'escape' becomes 'flee' (I've seen this before).
'by the sound of it' shows a homophone (sound like).
'flee' is a homophone of 'FLEA'.
'to' is the link.
(Other definitions for flea that I've seen before include "Leaping insects" , "In one's ear, it's a stinging rebuke" , "Biting type" , "Irritating jumper?" , "Jumping, blood-sucking insect" .)