Importance of fact to America? (6)
I believe the answer is:
status
'importance' is the definition.
(status is a kind of importance)
'fact to america?' is the wordplay.
'fact' becomes 'stat' (statistic).
'to america?' becomes 'US' (United States).
'stat'+'us'='STATUS'
'of' acts as a link.
(Other definitions for status that I've seen before include "legal position" , "High rank or prestige" , "Standing position, perhaps" , "Place in society" , "Importance (in society?)" .)