Old-fashioned doorman powerless, on reflection (5)
I believe the answer is:
retro
'old-fashioned' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
(Other definitions for retro that I've seen before include "Imitating an older style" , "Old-fashioned style" , "recreating the past for effect" , "Reminiscent of a past style" , "Describes the style of an earlier time, in short" .)