Picture one before game, excited (5)
I believe the answer is:
image
'picture' is the definition.
(I know that picture can be written as image)
'one before game excited' is the wordplay.
'one' becomes 'i' (Roman numeral).
'before' says to put letters next to each other.
'excited' indicates anagramming the letters.
'game' with letters rearranged gives 'mage'.
'i'+'mage'='IMAGE'
(Other definitions for image that I've seen before include "Metaphor; figure" , "Epitome" , "Likeness; statue" , "Picture (involving one letter change from 10)" , "Representation, picture" .)