One following fool gripping lead on rabid dog (6)
I believe the answer is:
borzoi
'dog' is the definition.
(borzoi is a kind of dog)
'one following fool gripping lead on rabid' is the wordplay.
'one' becomes 'I' (Roman numeral).
'following' is a charade indicator (letters next to each other).
'fool' becomes 'bozo' (bozo can mean a foolish person).
'gripping' indicates putting letters inside (inserted letters are gripped).
'lead on' suggests taking the first letters.
The initial letter of 'rabid' is 'r'.
'bozo' going around 'r' is 'borzo'.
'i' put after 'borzo' is 'BORZOI'.
(Other definitions for borzoi that I've seen before include "Russian wolfhound" , "White descendant of French settlers in Louisiana" , "Zoo rib (anag)" , "Dog like a huge greyhound" , "Russian dog bred for hunting wolves" .)