What could make hounds bay? (6)
I believe the answer is:
hudson
'bay?' is the definition.
(I've seen this before)
'what could make hounds' is the wordplay.
'what could make' is an anagram indicator.
'hounds' anagrammed gives 'HUDSON'.
(Other definitions for hudson that I've seen before include "8 [BUTLER" , "Rock -, - bay" , "NY river; Canadian Bay" , "Rock --, US actor" , "Large bay in Canada" .)