Duke and Arctic dog losing hour in dark (5)
I believe the answer is:
dusky
'dark' is the definition.
(similar in meaning)
'duke and arctic dog losing hour' is the wordplay.
'duke' becomes 'd' (abbreviation).
'and' is a charade indicator (letters next to each other).
'arctic dog' becomes 'husky' (I've seen this before).
'losing' indicates named letters should be taken away.
'hour' becomes 'h'.
'husky' with 'h' taken out is 'usky'.
'd'+'usky'='DUSKY'
'in' acts as a link.
(Other definitions for dusky that I've seen before include "Shadowy, darkish" , "Shadowy or dark-coloured" , "Dark-complexioned" , "Dark shaded" , "Swarthy" .)