One prone to histrionics in play group (5,5)
I believe the answer is:
drama queen
'one prone to histrionics' is the definition.
(I've seen this before)
'play group' is the wordplay.
'play' becomes 'drama' (synonyms).
'group' becomes 'Queen' (Queen are a band).
'drama'+'queen'='DRAMA QUEEN'
'in' acts as a link.
(Other definitions for drama queen that I've seen before include "Gertrude, perhaps" , "one excited often" , "is too fond of her scenes?" , "Male or female prone to histrionics" , "woman prone to histrionics" .)