Revived bar opening in Cambridge, light blue (9)
I believe the answer is:
clampdown
'revived bar' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'opening in cambridge light blue' is the wordplay.
'opening in' suggests taking the first letters.
'light' becomes 'lamp' (lamp is a kind of light).
'blue' becomes 'down' (both can mean sad).
The initial letter of 'cambridge' is 'c'.
'c'+'lamp'+'down'='CLAMPDOWN'
Can you help me to learn more?
(Other definitions for clampdown that I've seen before include "restrictive measure" , "Sudden restriction on an activity" , "stopper?" , "Restrictive practice" , "suppression" .)