First sinner no good round home in dusk (7)
I believe the answer is:
evening
'dusk' is the definition.
(I've seen this before)
'first sinner no good round home' is the wordplay.
'first sinner' becomes 'eve' (I've seen this in another clue).
'no good' becomes 'ng' (abbreviation).
'round' means one lot of letters goes inside another.
'home' becomes 'in' ('he's home' can mean 'he's in').
'ng' enclosing 'in' is 'ning'.
'eve'+'ning'='EVENING'
'in' acts as a link.
(Other definitions for evening that I've seen before include "Hours before bedtime" , "Dusk" , "The close of a day; a word used in the first ever 2 dn" , "twilight" , "Making uniform" .)