Was the elder one old Bill? (4)
I believe the answer is:
pitt
'elder one old bill?' is the definition.
The definition suggests a singular noun which matches the answer.
'was the' is the wordplay.
'was' becomes 'pit' (I can't explain this - if you can you should give a lot more credence to this answer).
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'pit'+'t'='PITT'
Can you help me to learn more?
(Other definitions for pitt that I've seen before include "old politician" , "Old British statesman" , "a name in politics once" , "William - the Younger, twice prime minister" , "Statesman, Earl of 10" .)