Act as a peacock's prop? (5)
I believe the answer is:
strut
I believe this clue is a double definition.
'act as a peacock's' is the first definition.
(strut around like a peacock)
'prop?' is the second definition.
(I've seen this before)
(Other definitions for strut that I've seen before include "Vain walk" , "Walk with proud and conceited gait" , "Walk with a lofty proud gait" , "Supporting bar" , "Walk proudly like bantam-cock" .)