Stylish groom? Yes, initially (6)
I believe the answer is:
dressy
'stylish' is the definition.
(in formal dress)
'groom? yes initially' is the wordplay.
I cannot really understand how this works, but
'groom?' could be 'dress' (dressing is a kind of grooming) and 'dress' is found within the answer.
'yes' could be 'y' and 'y' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for dressy that I've seen before include "Sartorially elegant" , "Wearing stylish clothes, elegant (6)" , "swish" , "Stylishly attired" , "Smartly clad, wearing stylish clothes" .)