Dog that is following explorer (7)
I believe the answer is:
scottie
'dog' is the definition.
(I know that Scottie is a type of dog)
'that is following explorer' is the wordplay.
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'following' says to put letters next to each other.
'explorer' becomes 'scott' (I have seen 'Antarctic explorer ' mean 'scott' so perhaps 'explorer' could also mean 'scott').
'ie' put after 'scott' is 'SCOTTIE'.
(Other definitions for scottie that I've seen before include "Type of terrier" , "Dog" , "Breed of terrier" , "animal" .)