In ill humour, pay out extremes of demand (5)
I believe the answer is:
paddy
'in ill humour' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'pay out extremes of demand' is the wordplay.
'out' is an insertion indicator.
'extremes of' says to hollow out the word (remove centre letters).
'demand' with its middle taken out is 'dd'.
'pay' placed around 'dd' is 'PADDY'.
Can you help me to learn more?
(Other definitions for paddy that I've seen before include "area for rice-growers" , "Rice-field" , "Sort of wagon" , "Temper tantrum" , "One regularly flooded" .)