Result of too much demand? Er, possibly! (8)
I believe the answer is:
shortage
'result of too much demand?' is the definition.
'shortage' can be an answer for 'demand?' (shortage is a kind of demand). I'm unsure of the 'result of too much' bit.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for shortage that I've seen before include "Dearth, lack" , "famine" , "Lack, deficiency" , "Want" , "Horse tag (anag.)" .)