We're out of wallop (such as chardonnay?) (5)
I believe the answer is:
white
'chardonnay?' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'we're out of wallop' is the wordplay.
'we're' becomes 'we' (I can't justify this - if you can you should believe this answer much more).
'out of' means one lot of letters goes inside another (some letters on the outside of others).
'wallop' becomes 'hit' (I've seen this in another clue).
'we' placed around 'hit' is 'WHITE'.
'such as' acts as a link.
Can you help me to learn more?
(Other definitions for white that I've seen before include "Bridal colour" , "Colour of milk" , "See 10" , "Colourless" , "Opponent of six dn (chess)" .)