Soak in dark rum, continue over days (8)
I believe the answer is:
drunkard
'soak' is the definition.
(I've seen this in another clue)
'in dark rum continue over days' is the wordplay.
'in' means one lot of letters goes inside another.
'rum' indicates an anagram (rum can mean strange or unusual).
'continue' becomes 'run' (running is a kind of continuing).
'over' means one lot of letters go next to another.
'days' becomes 'd' (abbreviation for days).
'dark' anagrammed gives 'dkar'.
'dkar' placed around 'run' is 'drunkar'.
'drunkar'+'d'='DRUNKARD'
(Other definitions for drunkard that I've seen before include "Sot, addicted drinker" , "boozer" , "alkie" , "One regularly intoxicated" , "Habitual inebriate" .)