For which Shaw wrote two articles, three on odd occasions (7)
I believe the answer is:
theatre
'for which shaw wrote' is the definition.
(George Bernard Shaw was a playwright)
'two articles three on odd occasions' is the wordplay.
'two articles' means two replacements for 'articles'.
'articles' becomes 'thea' (two examples of the part-of-speech: the+a).
'articles' says to put letters next to each other.
'on odd occasions' indicates alternate letters (the odd-numbered letters are used).
The alternating letters of 'three' are 'tre'.
'thea'+'tre'='THEATRE'
(Other definitions for theatre that I've seen before include "Audience" , "Hospital operating room - playhouse" , "Space for drama" , "Space for dramatid art" , "Place for dramatic performances" .)