Later on, I worried about member's gymnastic apparatus (10)
I believe the answer is:
trampoline
'gymnastic apparatus' is the definition.
(trampoline is a kind of gymnastic apparatus)
'later on i worried about member's' is the wordplay.
I cannot really understand how this works, but
'i' could be 'a' and 'a' is located in the answer.
'member' could be 'mp' and 'mp' is found in the answer.
This explanation may well be incorrect...
(Other definitions for trampoline that I've seen before include "Spring up" , "bouncer" , "Sprung gymnastic equipment" , "Trap oilmen (anag.)" , "On which bouncers go" .)