Advantage held by seed, generally (4)
I believe the answer is:
edge
'advantage' is the definition.
(edge is a kind of advantage)
'held by seed generally' is the wordplay.
'held by' indicates a hidden word.
'EDGE' is hidden within 'seed generally'.
(Other definitions for edge that I've seen before include "incisiveness" , "Rim - move gradually" , "Bite" , "marginal advantage" , "Margin, extremity" .)