Blustery at first with frequent showers, but bright (6)
I believe the answer is:
brainy
'bright' is the definition.
(both can mean intelligent)
'blustery at first with frequent showers' is the wordplay.
I cannot really see how this works, but
'at' could be 'in' (synonymous in some cases - eg at school, in school) and 'in' is found within the answer.
'first' could be 'a' (first letter of the alphabet) and 'a' is found in the answer.
This explanation may well be incorrect...
'but' is the link.
Can you help me to learn more?
(Other definitions for brainy that I've seen before include "Binary (anag.)" , "Intelligent, clever." , "Showing intelligence" , "smart?" , "Intellectual" .)