Double expectoration before single game's play (8,5)
I believe the answer is:
spitting image
'double' is the definition.
(I've seen this in another clue)
'expectoration before single game's play' is the wordplay.
'expectoration' becomes 'spitting' (synonyms).
'before' is a charade indicator (letters next to each other).
'single' becomes 'I' (one).
'play' is an anagram indicator.
'game' is an anagram of 'mage'.
'spitting'+'i'+'mage'='SPITTING IMAGE'
(Other definitions for spitting image that I've seen before include "Exact likeness" , "Exact double" , "Perfect likeness" , "exact copy" , "show on TV" .)