I'll go into lounge with champagne and a sweet (8)
I believe the answer is:
lollipop
'a sweet' is the definition.
(lollipop is a kind of sweet)
'i'll go into lounge with champagne' is the wordplay.
'i'll' becomes 'i' (this might be a standard abbreviation I've not previously seen).
'go into' is an insertion indicator (some letters go into others).
'lounge' becomes 'loll' (both can mean to sit in a relaxed way).
'with' says to put letters next to each other.
'champagne' becomes 'pop'.
'loll'+'pop'='lollpop'
'i' inserted within 'lollpop' is 'LOLLIPOP'.
'and' acts as a link.
(Other definitions for lollipop that I've seen before include "Sweet on a stick" , "Woman seeing children safely across the road" , "Confectionery" , "Nutcracker Suite, say" , "Sucked sweet" .)