Said only he’s a laughing-stock (4)
I believe the answer is:
butt
'stock' is the definition.
(butt is a kind of stock)
'said only' is the wordplay.
'said' shows a homophone (sound like).
'only' becomes 'but' (but can mean only - eg 'life is but a dream').
'but' sounds like 'BUTT'.
'he's a laughing' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for butt that I've seen before include "couple of hogsheads?" , "Fag-end" , "Hit with the head; object of ridicule" , "Contralto" , ""bottom" to US" .)