Saint always a support (4)
I believe the answer is:
stay
'a support' is the definition.
(stay is a kind of support)
'saint always' is the wordplay.
'saint' becomes 'st'.
'always' becomes 'ay'.
'st'+'ay'='STAY'
(Other definitions for stay that I've seen before include "Sojourn" , "Defer" , "Remain; detain" , "control" , "Delay (execution)" .)