Showy elderly relative does initially impressive cartwheels (9)
I believe the answer is:
grandiose
'showy' is the definition.
(thesaurus)
'elderly relative does initially impressive cartwheels' is the wordplay.
I cannot quite understand how this works, but
'relative' could be 'gran' (short for grandmother) and 'gran' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for grandiose that I've seen before include "Pretentiously magnificent" , "I grade son as affectedly splendid" , "affected" , "Ambitious" , "Bombastic" .)