Second mole eating daughter's creepy-crawly (6)
I believe the answer is:
spider
'creepy-crawly' is the definition.
(spider is a kind of invertebrate)
'second mole eating daughter's' is the wordplay.
'second' becomes 's' (common abbreviation).
'mole' becomes 'pier' (I've seen this in other clues).
'eating' indicates putting letters inside.
'daughter' becomes 'd' (genealogical abbreviation).
'pier' placed around 'd' is 'pider'.
's'+'pider'='SPIDER'
(Other definitions for spider that I've seen before include "website designer?" , "potter's accessory?" , "Prised open the arachnid" , "Harvester" , "Arthropod; snooker rest" .)