Morning custom which can cause laughter (5)
I believe the answer is:
amuse
'cause laughter' is the definition.
(I've seen this in another clue)
'morning custom' is the wordplay.
'morning' becomes 'am' (as in 12:00 AM).
'custom' becomes 'use' (use is a kind of custom).
'am'+'use'='AMUSE'
'which can' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for amuse that I've seen before include "Beguile" , "interest" , "Cause mirth - distract" , "Keep someone entertained" , "Enliven" .)