Tube avoided, say (4)
I believe the answer is:
duct
'tube' is the definition.
(I've seen this before)
'avoided say' is the wordplay.
'avoided' becomes 'ducked' (ducking is a kind of avoiding).
'say' shows a homophone (sound like).
'ducked' is a homophone of 'DUCT'.
(Other definitions for duct that I've seen before include "Passage for cables etc." , "Tube for conveing cable, liquid etc" , "Pipe conveying fluid or gas" , "Tube for cables, air, etc" , "Tube, passageway" .)