Whatever starts to make everyone happy (3)
I believe the answer is:
meh
'whatever' is the definition.
(I've seen this in another clue)
'starts to make everyone happy' is the wordplay.
'starts to' suggests taking the first letters.
The first letters of 'make everyone happy' is 'MEH'.
(Other definitions for meh that I've seen before include "am I bovvered?" , "Not much cop" , "expression of indifference" , "Who cares" , "Unexciting (modern slang)" .)