Importunate nun snubbed in pub over time (9)
I believe the answer is:
insistent
'importunate' is the definition.
(thesaurus)
'nun snubbed in pub over time' is the wordplay.
'nun' becomes 'sister' (a nun might be called sister).
'snubbed' means to remove the last letter (could historically mean cutting the end off).
'in' is an insertion indicator.
'pub' becomes 'inn' (an inn is a type of pub).
'over time' becomes 't' (abbreviation. I am not sure about the 'over' bit.).
'sister' with its final letter taken away is 'siste'.
'siste' inserted inside 'inn' is 'insisten'.
'insisten'+'t'='INSISTENT'
Can you help me to learn more?
(Other definitions for insistent that I've seen before include "Declaring or demanding emphatically" , "Emphatic" , "Compelling attention" , "Determined" , "Unwilling to take "no" for an answer" .)