Take vain steps to provide support (5)
I believe the answer is:
strut
I believe this is a double definition.
'take vain steps' is the first definition.
(I've seen this before)
'support' is the second definition.
(strut is a kind of support)
'to provide' acts as a link.
(Other definitions for strut that I've seen before include "Walk proudly like metal support" , "Walk arrogantly" , "Strengthening bar" , "Walk proudly like bantam-cock" , "Reinforcing rod" .)