Wit coming from British weather authority (10)
I believe the answer is:
brainpower
'wit' is the definition.
(I know that wit can be written as brainpower)
'british weather authority' is the wordplay.
'british weather' becomes 'brain' (I can't justify this - if you can you should give a lot more credence to this answer).
'authority' becomes 'power' (I've seen this in another clue).
'brain'+'power'='BRAINPOWER'
'coming from' acts as a link.
Can you help me to learn more?
(Another definition for brainpower that I've seen is " intelligence".)