It's back in the Channel site! (4)
I believe the answer is:
isle
'it's' is the definition.
I can't tell whether this defines the answer.
'back in the channel site' is the wordplay.
'back' is a reversal indicator.
'in' indicates the answer is hidden within the clue.
'elsi' is hidden within 'channel site'.
'elsi' in reverse letter order is 'ISLE'.
Can you help me to learn more?
(Other definitions for isle that I've seen before include "like 'Hoy!'" , "Eg, Iona" , "Man, maybe" , "___ of Dogs, Man or Skye" , "one has water all round" .)