"Not so good" (3)
'not so good' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for worse that I've seen before include "More severe; less well" , "More awful or unwell" , "Less favourable" , "Less good" , "Of poorer quality" .)
(Other definitions for meh that I've seen before include "am I bovvered?" , "expression of indifference" , "Not much cop" , "Unexciting (modern slang)" , "Who cares" .)