Live in impressive tower (7)
I believe the answer is:
minaret
'tower' is the definition.
(minaret is a kind of tower)
'live in impressive' is the wordplay.
'live' becomes 'are' (both can mean exist).
'in' means one lot of letters goes inside another.
'impressive' becomes 'mint' (I am not sure about this - if you are sure you should believe this answer much more).
'are' placed within 'mint' is 'MINARET'.
Can you help me to learn more?
(Other definitions for minaret that I've seen before include "Mosque spire" , "Slender mosque tower" , "Muezzin's tower" , "Slender tower with balconies" , "religious tower" .)