Entirely because of article on stadium (4,2,3,6)
I believe the answer is:
down to the ground
'entirely' is the definition.
(I've seen this before)
'because of article on stadium' is the wordplay.
'because of' becomes 'downto'.
'article' becomes 'the' (the 'definite article' part of speech).
'on' says to put letters next to each other.
'stadium' becomes 'ground' (I've seen this before).
'downto'+'the'+'ground'='DOWN TO THE GROUND'
(Other definitions for down to the ground that I've seen before include "So well suited" , "How paras come" , "In every respect" , "Where rain goes" , "football fan travelling here?" .)