Walk ostentatiously to show support (5)
I believe the answer is:
strut
I believe this is a double definition.
'walk ostentatiously' is the first definition.
(as in strutting one's stuff)
'support' is the second definition.
(strut is a kind of support)
'to show' is the link.
(Other definitions for strut that I've seen before include "swaggering gait" , "supporter" , "Swagger; bracing bar" , "Reinforcing rod" , "Walk arrogantly" .)