Ruining meal that's eaten cold with mixed gin (10)

'ruining' is the definition.
Although both the answer and definition are present participle verbs, I don't see how they can define each other.

'meal that's eaten cold with mixed gin' is the wordplay.
'meal' becomes 'supper' (supper is a kind of meal).
'that's eaten' is an insertion indicator (some letters have eaten others).
'cold' becomes 'c' (eg on taps).
'with' means one lot of letters go next to another.
'mixed' indicates an anagram.
'supper' placed around 'c' is 'scupper'.
'gin' is an anagram of 'ing'.
'scupper'+'ing'='SCUPPERING'

Can you help me to learn more?