This club is much patronised by gymnasts (6)
I believe the answer is:
indian
'this club' is the definition.
(Indian club is an example)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for indian that I've seen before include "Type of ink or summer" , "Type of club, file, tea or summer" , "Native American or denizen of New Delhi, say" , "One from the sub-continent" , "IDA inn provided for this notionality" .)