Open with a play by GB Shaw (7)
I believe the answer is:
candida
'play by gb shaw' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'open with a' is the wordplay.
'open' becomes 'candid' (I've seen this in another clue).
'with' is a charade indicator (letters next to each other).
'candid'+'a'='CANDIDA'
Can you help me to learn more?
(Other definitions for candida that I've seen before include "Fungus" , "by G.B. Shaw" , "Parasite" , "GBS play" .)