Trial in old era, disorderly (6)
I believe the answer is:
ordeal
'trial' is the definition.
(I've seen this in another clue)
'old era disorderly' is the wordplay.
'disorderly' indicates anagramming the letters.
'old'+'era'='oldera'
'oldera' with letters rearranged gives 'ORDEAL'.
'in' is the link.
(Other definitions for ordeal that I've seen before include "Tribulation" , "Disturbing experience" , "Long, unpleasant experience" , "Severe or trying experience" , "Difficult and testing experience" .)