Dogs, say, misleading guards (4)
I believe the answer is:
isle
'dogs say' is the definition.
(Isle of Dogs)
'misleading guards' is the wordplay.
'guards' indicates a hidden word.
'ISLE' is hidden within 'misleading'.
(Other definitions for isle that I've seen before include "Small island" , "one ringed in the main?" , "Rum, for example" , "Lies (anag)" , "Spot (in ocean)" .)