Lifting barrel to find seed (3)
I believe the answer is:
nut
'seed' is the definition.
(nut is a kind of seed)
'lifting barrel' is the wordplay.
'lifting' says the letters should be written backwards.
'barrel' becomes 'tun' (tun is a kind of barrel).
'tun' backwards is 'NUT'.
'to find' acts as a link.
(Other definitions for nut that I've seen before include "Fruit with hard shell" , "Hard fruit; obsessive" , "something turned when making fast > food" , "Seed with hard shell and firm kernel" , "eg Almond, brazil" .)