Crowd turned red after laugh (5)
I believe the answer is:
horde
'crowd' is the definition.
(I know that horde is a type of crowd)
'turned red after laugh' is the wordplay.
'turned' indicates an anagram.
'after' means one lot of letters go next to another.
'laugh' becomes 'ho' (representation of a laughing sound).
'red' anagrammed gives 'rde'.
'rde' put after 'ho' is 'HORDE'.
(Other definitions for horde that I've seen before include "Large group of people" , "A swarm or multitude" , "Great crowd" , "A moving crowd" , "Host" .)