Electoral indicator, maybe, with number on Big Ben? (10)
I believe the answer is:
bellwether
'electoral indicator' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'with number on big ben?' is the wordplay.
'with' becomes 'w' (abbreviation).
'number' becomes 'ether' (anaesthetic, something which numbs).
'on' is a charade indicator (letters next to each other).
'big ben?' becomes 'bell' (I can't justify this - if you can you should give a lot more credence to this answer).
'w'+'ether'='wether'
'wether' put after 'bell' is 'BELLWETHER'.
'maybe' is the link.
Can you help me to learn more?
(Other definitions for bellwether that I've seen before include "Leader of the flock" , "Sheep that leads the flock -- we tell Herb (anag)" , "Leading sheep of a flock" , "Leading sheep; trendsetter" .)