In conclusion, good time promised (7)
I believe the answer is:
engaged
'promised' is the definition.
(synonyms)
'in conclusion good time' is the wordplay.
'in' means one lot of letters goes inside another.
'conclusion' becomes 'end' (end is a kind of conclusion).
'good' becomes 'g' (abbreviation).
'time' becomes 'age' (an age is a period of time).
'g'+'age'='gage'
'end' enclosing 'gage' is 'ENGAGED'.
(Other definitions for engaged that I've seen before include "looking forward to the match?" , "Bethrothed" , "preparing for the match?" , "Occupied with business - about to marry?" , "tied up" .)