Encourage factory to produce a vegetable (8)
I believe the answer is:
eggplant
'a vegetable' is the definition.
(I know that eggplant is a vegetable)
'encourage factory' is the wordplay.
'encourage' becomes 'egg'.
'factory' becomes 'plant' (a manufacturing plant).
'egg'+'plant'='EGGPLANT'
'to produce' acts as a link.
(Other definitions for eggplant that I've seen before include "Vegetable" , "US name for aubergine" , "What goes into moussaka" , "Another word for aubergine" , "It's also called aubergine" .)