In this case it's raining and everybody goes inside (6)
I believe the answer is:
wallet
'in this case it's raining' is the definition.
'wallet' can be an answer for 'case' (wallet is a kind of case). I am unsure of the rest of the definition.
'everybody goes inside' is the wordplay.
'everybody' becomes 'wall' (I can't justify this - if you can you should believe this answer much more).
'goes' becomes 'gets' ('get' can be a synonym of 'go').
'inside' says to take the centre.
The middle letters of 'gets' are 'et'.
'wall'+'et'='WALLET'
'and' is the link.
Can you help me to learn more?
(Other definitions for wallet that I've seen before include "Billfold (US)" , "Notecase" , "Purse for notes" , "Shepherdess of rhyme" , "A man's pocket-book" .)