Department cuts out channels (5)
I believe the answer is:
ducts
'channels' is the definition.
(I know this)
'department cuts out' is the wordplay.
'department' becomes 'd' (abbreviation eg in MOD Ministry of Defence).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'cuts' with letters rearranged gives 'ucts'.
'd'+'ucts'='DUCTS'
(Other definitions for ducts that I've seen before include "Enclosed conduits for fluid" , "Channels" .)