18 Vile wretch planned crimes against a conservation charity(9)
Anag of six letter word in clue + abbrevation for a national countryside body. - the whole is another word for a vile wretch.
28 Threaten and complain if the food is canned or pickled(5,4)
word for threaten + word for complain - answer is a bit meaty.
59 Ronald took part in a crooked deal with the robber(7)]
abbreviation of given name inside anagram of a four letter word in the clue. - gives a word meaning a robber or a pirate
82 Criminal to display such dirty armour before the Queen (11)
Word meaning dirty + word for type of armour + abbreviation for queen. - Think Letterman
Hope these clues help.