Gloomy in local eating empty 'Scotch' dish (8)
I believe the answer is:
negative
'gloomy' is the definition.
(thesaurus)
'local eating empty scotch dish' is the wordplay.
'local' becomes 'native' (similar in meaning).
'eating' is an insertion indicator.
'empty' says to hollow out the word (remove centre letters).
'scotch dish' becomes 'egg' (as in a Scotch egg).
'egg' with its middle removed is 'eg'.
'native' placed around 'eg' is 'NEGATIVE'.
'in' is the link.
(Other definitions for negative that I've seen before include "Less than zero, minus" , "Expressing or implying denial or refusal" , "Photographic image with tones reversed" , "Not positive - denial" , "Reply of denial" .)