Street ad I and you say means open sport facility (7)
I believe the answer is:
stadium
'sport facility' is the definition.
(I know that Stadium is a type of sport facility)
'street ad i and you say means open' is the wordplay.
'street' becomes 'st' (abbreviation).
'and' says to put letters next to each other.
'you say' becomes 'u' ('you' as it sounds).
'open' indicates taking the first letters (I've seen 'opens' mean this).
The initial letter of 'means' is 'm'.
'st'+'ad'+'i'+'u'+'m'='STADIUM'
(Other definitions for stadium that I've seen before include "Large structure for open-air sports" , "Sports ground as for athletics" , "Sports arena" , "eg Yankee, Wembley" , "Venue for sporting events, concerts etc" .)