Why don't we return from the wastelands! (4)
I believe the answer is:
lets
'why don't we' is the definition.
(I've seen this in another clue)
'return from the wastelands' is the wordplay.
'return' says the letters should be written backwards.
'from' indicates a hidden word.
'stel' is hidden within 'wastelands'.
'stel' in reverse letter order is 'LETS'.
(Other definitions for lets that I've seen before include "Rents out or allows" , "Permits" , "we shall serve them again!" , "Yes" , "Leases" .)