Vegan data possibly showing benefit (9)
I believe the answer is:
advantage
'benefit' is the definition.
(I've seen this before)
'vegan data possibly' is the wordplay.
'possibly' indicates anagramming the letters.
'vegan'+'data'='vegandata'
'vegandata' is an anagram of 'ADVANTAGE'.
'showing' acts as a link.
(Other definitions for advantage that I've seen before include "Privilege" , "Edge, head start" , "Favourable circumstance" , "Benefit, profit" , "Asset" .)