Trustworthy English writer turning naughty, led off outside (10)
I believe the answer is:
dependable
'trustworthy' is the definition.
(associated in meaning)
'english writer turning naughty led off outside' is the wordplay.
'english writer' becomes 'epen' (I am not sure about this - if you are sure you should believe this answer much more).
'turning' says the letters should be written backwards.
'naughty' becomes 'bad' (badly behaved).
'off' is an anagram indicator.
'outside' indicates putting letters inside.
'bad' back-to-front is 'dab'.
'led' is an anagram of 'dle'.
'epen'+'dab'='ependab'
'ependab' going within 'dle' is 'DEPENDABLE'.
(Another definition for dependable that I've seen is " Trustworthy, reliable".)