Chain to a London bridge (6)
I believe the answer is:
albert
'chain' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for albert that I've seen before include "watch may depend on it" , "Old watch chain" , "chap" , "Victim of lion" , "and 7: French missionary" .)