Why bride's somewhat cross? (6)
I believe the answer is:
hybrid
'cross?' is the definition.
(I know that cross can be written as hybrid)
'why bride's somewhat' is the wordplay.
'somewhat' says the answer is hidden in the clue.
'HYBRID' is hidden within 'why brides'.
(Other definitions for hybrid that I've seen before include "Cross breed" , "Of mixed ancestry" , "Genetic cross" , "Like a mule" , "Plant grown from two different species" .)