Channel going in deep I pulled towards the surface? (4)
I believe the answer is:
pipe
'channel' is the definition.
(pipe is a kind of channel)
'going in deep i pulled towards the surface?' is the wordplay.
'going in' indicates the answer is hidden within the clue.
'towards the surface?' says the letters should be written backwards (in a down clue, letters go up).
'epip' is hidden in the letters of 'deep i pulled'.
'epip' reversed gives 'PIPE'.
(Other definitions for pipe that I've seen before include "Whistle" , "Utter shrilly; wine cask" , "Tube with bowl for smoking tobacco" , "Tube carrying liquid or gas" , "Transmit through a tube" .)