Well-versed in games, one maintains (8)
I believe the answer is:
supports
'one maintains' is the definition.
I can't judge whether this defines the answer.
'well-versed in games' is the wordplay.
'well versed' becomes 'up' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'games' becomes 'sports' (I've seen this before).
'up' inserted within 'sports' is 'SUPPORTS'.
Can you help me to learn more?
(Other definitions for supports that I've seen before include "Tees" , "Bears the weight of" , "Backs or approves of" , "Helps" , "Holds up" .)