Kind of lease broken by a Conservative (9)
I believe the answer is:
character
'kind' is the definition.
(thesaurus)
'lease broken by a conservative' is the wordplay.
'lease' becomes 'charter' (synonyms).
'broken by' indicates putting letters inside (inserted letters break into the word).
'conservative' becomes 'C' (UK political abbreviation).
'a'+'c'='ac'
'charter' going around 'ac' is 'CHARACTER'.
'of' is the link.
(Other definitions for character that I've seen before include "Person in a novel or play" , "Nature; good reputation" , "Quality" , "strength of mind" , "Type - letter" .)