Sauce required for formal dinner (8)
I believe the answer is:
dressing
'sauce' is the definition.
(I know that dressing is a type of sauce)
'formal dinner' is the wordplay.
'formal' becomes 'dress' (similar in meaning).
'dinner' becomes 'ing' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'dress'+'ing'='DRESSING'
'required for' is the link.
Can you help me to learn more?
(Other definitions for dressing that I've seen before include "clothing" , "Sauce for salads" , "Sauce - protection for wound" , "plaster, for example?" , "Sauce - alignment - bandage" .)