Great significance or value (10)
I believe the answer is:
importance
This clue is a double definition.
'great significance' is the first definition.
(I've seen this before)
'value' is the second definition.
(I know that importance is a type of value)
(Other definitions for importance that I've seen before include "value" , "moment" , "See 6" , "standing" , "Great significance" .)