Tiny packets, as can hide insect (6)
I believe the answer is:
quanta
'tiny packets' is the definition.
(a quantum is subatomic packet of energy)
'as can hide insect' is the wordplay.
'as' becomes 'qua' (I've seen this before).
'can hide' is an insertion indicator.
'insect' becomes 'ant' (ant is a kind of insect).
'qua' placed around 'ant' is 'QUANTA'.
(Other definitions for quanta that I've seen before include "Smallest amounts in physics" , "Packets of energy" , "Smallest discrete amounts" .)