Plant is fine further down (6)
I believe the answer is:
flower
'plant' is the definition.
(flower is a kind of plant)
'fine further down' is the wordplay.
'fine' becomes 'f' (abbreviation).
'further down' becomes 'lower' (I've seen this before**).
'f'+'lower'='FLOWER'
'is' is the link.
(Other definitions for flower that I've seen before include "prime of life" , "Bloom" , "One found in bed perhaps" , "Blossom" , "Garden plant" .)