Herb had years to build shop (12)
I believe the answer is:
haberdashery
'shop' is the definition.
(haberdashery is a kind of shop)
'herb had years to build' is the wordplay.
'to build' indicates anagramming the letters.
'herb'+'had'+'years'='herbhadyears'
'herbhadyears' with letters rearranged gives 'HABERDASHERY'.
(Other definitions for haberdashery that I've seen before include "Sewing accessories" , "Pins and needles etc." , "Buttons, thread, etc." , "shop" , "Buttons and bows etc" .)