In smithy, bride's cross (6)
I believe the answer is:
hybrid
'cross' is the definition.
(thesaurus)
'in smithy bride's' is the wordplay.
'in' says the answer is hidden in the clue.
'HYBRID' is hidden within 'smithy brides'.
(Other definitions for hybrid that I've seen before include "Cross breed" , "Mongrel - cross" , "Produced by crossbreeding" , "Of mixed character" , "Plant grown from two different species" .)