Naughty terrier? Salt of the earth! (11)
I believe the answer is:
terrestrial
'of the earth' is the definition.
(I've seen this before)
'naughty terrier? salt' is the wordplay.
'naughty' indicates an anagram.
'terrier'+'salt'='terriersalt'
'terriersalt' with letters rearranged gives 'TERRESTRIAL'.
(Other definitions for terrestrial that I've seen before include "Not aquatic, arboreal, or aerial" , "Land-based" , "Relating to the earth" , "Living on the ground" , "Relating to dry land" .)