Insects need septic tanks (10)
I believe the answer is:
centipedes
'insects' is the definition.
(centipedes are insect-like creatures)
'need septic tanks' is the wordplay.
'tanks' indicates anagramming the letters (tank can mean to fail or go wrong).
'need'+'septic'='needseptic'
'needseptic' with letters rearranged gives 'CENTIPEDES'.
(Other definitions for centipedes that I've seen before include "Bugs" , "Crawlers" .)