Flowering potatoes, say, to appear out of the earth (7)
I believe the answer is:
outcrop
'appear out of the earth' is the definition.
(an outcrop is a rock formation on the surface)
'flowering potatoes say' is the wordplay.
'flowering' becomes 'out' (plants which are currently flowering are 'out').
'potatoes say' becomes 'crop'.
'out'+'crop'='OUTCROP'
'to' is the link.
(Other definitions for outcrop that I've seen before include "Rock standing proud" , "Rocky feature" , "Rocks appearing at the surface" , "Jutting stone" , "Visible rock formation" .)