College to attempt to suppress article as a whole (7)
I believe the answer is:
Here is my best explanation:
'a whole' is the definition.
'college to attempt to suppress article' is the subsidiary indication.
'college' becomes 'uni' (I've seen this in other clues**).
'to attempt' becomes 'try' ('try' can be a synonym of 'attempt').
'to suppress' means one lot of letters goes inside another.
'article' becomes 'a' (example of the part-of-speech).
'try' enclosing 'a' is 'tary'.
'as' is the link.
(Other definitions for unitary that I've seen before include "Single; uniform", "as a whole", "showing one nature" and "Marked by oneness".)