Support — rugby player (4)
I believe the answer is:
prop
I believe this is a double definition.
'support' is the first definition.
(prop up can mean to support)
'rugby player' is the second definition.
(type of rugby player)
(Other definitions for prop that I've seen before include "Back up" , "What actor may carry" , "one playing Rugby" , "Person or thing providing support" , "Seize and hold firmly" .)