Is taken aback a small amount about network making hissing sound (8)
I believe the answer is:
sibilant
'hissing sound' is the definition.
(an S sound)
'is taken aback a small amount about network' is the wordplay.
'taken aback' says the letters should be written in reverse.
'a small amount' becomes 'bit' (a bit is a small amount).
'about' indicates putting letters inside.
'network' becomes 'LAN' (Local Area Network).
'is' backwards is 'si'.
'bit' enclosing 'lan' is 'bilant'.
'si'+'bilant'='SIBILANT'
'making' acts as a link.
(Other definitions for sibilant that I've seen before include "Having a hissing sound as in speech" , "Consonant with a hissing sound" .)