One dwelt towards the north, given case of Scotch that's very bad (8)
I believe the answer is:
devilish
'very bad' is the definition.
'devilish' can be an answer for 'bad' (thesaurus). I am not sure about the 'very' bit.
'one dwelt towards the north given case of scotch' is the wordplay.
'one' becomes 'I' (Roman numeral).
'dwelt' becomes 'lived' ('live' can be a synonym of 'dwell').
'towards the north' says the letters should be written backwards (in a down clue, letters go up or head 'north').
'given' says to put letters next to each other.
'case of' says to hollow out the word (remove centre letters) (outsides of).
'scotch' with its centre taken out is 'sh'.
'lived' reversed gives 'devil'.
'i' after 'devil' is 'devili'.
'devili'+'sh'='DEVILISH'
'that's' is the link.
Can you help me to learn more?
(Other definitions for devilish that I've seen before include "like Screwtape" , "naughty" , "Very difficult to deal with" , "Very wicked" , "Diabolical" .)