Leads of terriers you petted, exceptionally kind (4)
I believe the answer is:
type
'kind' is the definition.
(type is a kind of kind)
'leads of terriers you petted exceptionally' is the wordplay.
'leads of' says to take the initial letters (I've seen 'leading' mean this).
The first letters of 'terriers you petted exceptionally' is 'TYPE'.
(Other definitions for type that I've seen before include "get words on to paper?" , "Category; use keyboard" , "Kind; set in print" , "Print form" , "The face" .)