Gasometer broken in very large shop (9)
I believe the answer is:
megastore
'very large shop' is the definition.
(I've seen this before)
'gasometer broken' is the wordplay.
'broken' indicates an anagram.
'gasometer' with letters rearranged gives 'MEGASTORE'.
'in' is the link.
(Other definitions for megastore that I've seen before include "Very large shop" , "Massive outlet" , "large outlet" , "giant in business" .)