In short, era itself deliberately old-fashioned (5)
I believe the answer is:
retro
'old-fashioned' is the definition.
(retro can mean reminiscent of past fashions)
'in short era itself deliberately' is the wordplay.
'RETRO' is hidden back-to-front in amongst the letters.
But, I am unsure how this is indicated.
Can you help me to learn more?
(Other definitions for retro that I've seen before include "Old-fashioned style" , "Imitating a bygone style" , "in nostalgic style" , "Style derived from the past" , "recapturing the past" .)