When Westminster quietens, that keeps the wet lot on edge (5,6)
I believe the answer is:
silly season
'edge' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'when westminster quietens that keeps the wet lot' is the wordplay.
I cannot quite see how this works, but
'when' could be 'on' (I've seen this in other clues) and 'on' is present in the answer.
'lot' could be 'ill' (ill is a kind of lot) and 'ill' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'on' acts as a link.
Can you help me to learn more?
(Other definitions for silly season that I've seen before include "Time for trivial news" , "When journo jokes" , "Period prone to frivolous news stories" , "Late summer period when there is little real news" , "Crazy time" .)