Water barrier in Canada maybe (3)
I believe the answer is:
dam
'water barrier' is the definition.
(I've seen this before)
'in canada maybe' is the wordplay.
'in' says the answer is hidden in the clue.
'DAM' can be found hidden inside 'canada maybe'.
(Other definitions for dam that I've seen before include "Female parent of an animal, especially livestock" , "Weir" , "Reservoir barrier" , "Mad as an animal mum" , "Mother - barrier" .)