Quiet trip before marriage causes loud quarrel (8,5)
I believe the answer is:
shouting match
'loud quarrel' is the definition.
(I've seen this before)
'quiet trip before marriage' is the wordplay.
'quiet' becomes 'sh'.
'trip' becomes 'outing' (I've seen this before**).
'before' means one lot of letters go next to another.
'marriage' becomes 'match' (I've seen this before).
'sh'+'outing'+'match'='SHOUTING MATCH'
'causes' is the link.
(Other definitions for shouting match that I've seen before include "Loud quarrel (colloq.)" , "row" .)