Participating researcher assesses distinct periods of history (4)
I believe the answer is:
eras
'distinct periods of history' is the definition.
(I've seen this before)
'participating researcher assesses' is the wordplay.
'ERAS' is hidden in amongst the letters.
However, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for eras that I've seen before include "Periods of time" , "Periods, ages" , "Long and distinct periods of history" , "typeface" , "Epochs" .)