Henry and Brunel will stop Carol and Bob once (8)
I believe the answer is:
shilling
'bob once' is the definition.
'shilling' can be an answer for 'bob' (I've seen this before). I'm not sure about the 'once' bit.
'henry and brunel will stop carol' is the wordplay.
'henry' becomes 'H' (symbol for the unit of electrical inductance).
'and' is a charade indicator (letters next to each other).
'brunel will' becomes 'I'll' (where the crossword setter is 'Brunel').
'stop' means one lot of letters goes inside another (stopping can mean blocking a gap).
'carol' becomes 'sing' (carol can mean to sing carols).
'h'+'ill'='hill'
'hill' put inside 'sing' is 'SHILLING'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for shilling that I've seen before include "Old unit of imperial money, worth 12 pence" , "Old piece" , "Bob" , "Until 1971, ready here" , "soldier once took it from the King" .)