Sally's kind, that is (6)
I believe the answer is:
sortie
'sally's' is the definition.
('sortie' can be a synonym of 'sally')
'kind that is' is the wordplay.
'kind' becomes 'sort' ('sort' can be a synonym of 'kind'**).
'that is' becomes 'ie' ('i.e.' can be a synonym of 'that is').
'sort'+'ie'='SORTIE'
(Other definitions for sortie that I've seen before include "Offensive" , "Short trip; attack" , "Attack by a besieged garrison" , "(Siege) breakout" , "Attack launched from place of siege" .)