Mo -- Grade I funny character! (8)
I believe the answer is:
ideogram
'character' is the definition.
(ideogram is a kind of character)
'mo grade i funny' is the wordplay.
'funny' indicates anagramming the letters.
'mo'+'grade'+'i'='mogradei'
'mogradei' with letters rearranged gives 'IDEOGRAM'.
(Other definitions for ideogram that I've seen before include "Symbol indicating idea of a thing, like number" , "bit of kanji?" , "E.g. numeral, Chinese character" , "Symbol indicating idea, like road sign" , "Written character symbolising a concept or the thing itself" .)