An energy shortage leads to this idiot blushing (9)
I believe the answer is:
tiredness
'an energy shortage' is the definition.
The definition and answer can be both states of affairs as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'leads to this idiot blushing' is the wordplay.
'leads to' says to take the initial letters.
'blushing' becomes 'redness' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The first letters of 'this idiot' is 'ti'.
'ti'+'redness'='TIREDNESS'
Can you help me to learn more?
(Other definitions for tiredness that I've seen before include "Weary feeling" , "Residents in state of fatigue" , "That's liable to occur at midnight" , "Weariness" , "Exhaustion" .)