Put straight tabloid's missing section with ferocious expression (7)
I believe the answer is:
unsnarl
'put straight' is the definition.
(thesaurus)
'tabloid's missing section with ferocious expression' is the wordplay.
'tabloid' becomes 'Sun' (The Sun, UK newspaper).
'missing' indicates named letters should be taken away.
'section' becomes 's' (legal abbreviation).
'with' is a charade indicator (letters next to each other).
'ferocious expression' becomes 'snarl' (a snarl is a fierce or ferocious expression).
'sun' with 's' removed is 'un'.
'un'+'snarl'='UNSNARL'
(Another definition for unsnarl that I've seen is " Disentangle".)