Will have it one's exterior isn't to be renovated (6)
I believe the answer is:
insist
'will have' is the definition.
'insist' can be an answer for 'have' (thesaurus). I'm unsure of the 'will' bit.
'it one's exterior isn't to be renovated' is the wordplay.
I cannot quite understand how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
'one's' could be 'is' (roman numeral) and 'is' is present in the answer.
The remaining letters 'ins' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for insist that I've seen before include "Demand firmly" , "'Demand, make sure (6)'" , "express convinced viewpoint" , "Press" , "Assert firmly" .)