Share in growing concern? (9)
I believe the answer is:
allotment
I believe this clue is a double definition.
'share' is the first definition.
(allotment is a kind of share)
'growing concern?' is the second definition.
(place for growing vegetables)
'in' is the link.
(Other definitions for allotment that I've seen before include "Plot of public land rented to an individual for gardening" , "Where vegetables may be produced" , "growing area?" , "Portion, distribution" , "cultivated area" .)