Validated on social media almost the same day (5)
I believe the answer is:
liked
'validated on social media' is the definition.
(as in 'liking' a post on social media)
'almost the same day' is the wordplay.
'almost the same' becomes 'like' (like means similar).
'day' becomes 'd' (abbreviation for day).
'like'+'d'='LIKED'
(Other definitions for liked that I've seen before include "Took pleasure in" , "Was fond of" , "Enjoyed - popular" , "Appreciated" .)