Insect stage between larva and adult (4)
I believe the answer is:
pupa
'insect stage between larva and adult' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for pupa that I've seen before include "middle stage" , "not yet adult" , "Immature insect" , "Stage of an insect's development" , "creepy-crawly" .)