Rubbish excursion with sweetheart (5)
I believe the answer is:
tripe
'rubbish' is the definition.
(both can mean nonsense)
'excursion with sweetheart' is the wordplay.
'excursion' becomes 'trip' (a trip is an excursion or outing).
'with' is a charade indicator (letters next to each other).
'sweetheart' becomes 'e' (the middle letter or heart of 'sweet').
'trip'+'e'='TRIPE'
(Other definitions for tripe that I've seen before include "Rhubarb" , "Pants" , "Something to eat" , "Edible lining of cow's stomach - rubbish" , "Rot" .)