Unusually early to accept it as the truth (7)
I believe the answer is:
reality
'the truth' is the definition.
(I've seen this in another clue)
'unusually early to accept it' is the wordplay.
'unusually' is an anagram indicator.
'to accept' indicates putting letters inside.
'early' anagrammed gives 'realy'.
'realy' placed around 'it' is 'REALITY'.
'as' acts as a link.
(Other definitions for reality that I've seen before include "Truth, actuality" , "Fact" , "The world as it is" , "Type of television" , "All that is actual and not imaginary" .)