Where a panorama lacks a pictorial centrepiece! (6)
I believe the answer is:
panama
This clue could be a double definition.
'where a panorama lacks' is the first definition.
The answer is a location as well as being a singular noun. This is suggested by the definition.
'a pictorial centrepiece' is the second definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
Can you help me to learn more?
(Other definitions for panama that I've seen before include "Hat made of plaited palm leaves" , "Wide-brimmed hat" , "Central American country" , "A great canal or a straw hat" , "'Country, canal and hat (6)'" .)