Most agree it could be an eyesore (9)
I believe the answer is:
gasometer
'an eyesore' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'most agree it could be' is the wordplay.
'it could be' indicates anagramming the letters (the same letters could be an anagram).
'most'+'agree'='mostagree'
'mostagree' with letters rearranged gives 'GASOMETER'.
Can you help me to learn more?
(Other definitions for gasometer that I've seen before include "could be seen by the Oval" , "Large fuel tank" , "Game store (anag) - fuel store" , "source of fuel" , "Fuel storage tank" .)