Darwin's survivors set it out in newspaper (7)
I believe the answer is:
fittest
'darwin's survivors' is the definition.
(Charles Darwin, survival of the fittest)
'set it out in newspaper' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'in' indicates putting letters inside.
'newspaper' becomes 'FT' (Financial Times newspaper).
'set'+'it'='setit'
'setit' anagrammed gives 'ittes'.
'ittes' inserted into 'ft' is 'FITTEST'.
(Other definitions for fittest that I've seen before include "'Survival of the - - '" , "most sound" , "superlatively healthy" , "Healthiest" , "Most suitable" .)