Old politician's wife out — heat up meal (4,3)
I believe the answer is:
high tea
'meal' is the definition.
(I know that high tea is a type of dinner time)
'old politician's wife out heat up' is the wordplay.
'old politician' becomes 'whig' (Whigs were a historical British political party).
'wife' becomes 'w'.
'out' is a deletion indicator.
'up' indicates anagramming the letters (letters get chucked up).
'whig' with 'w' taken out is 'hig'.
'heat' anagrammed gives 'htea'.
'hig'+'htea'='HIGH TEA'
(Other definitions for high tea that I've seen before include "Late-afternoon meal" , "Early-evening meal" , "A lofty kind of evening meal" , "Early evening meal" , "Late afternoon meal which includes a cooked dish" .)