Napoleonic battle seen in mundane journal picked up (4)
I believe the answer is:
jena
'napoleonic battle' is the definition.
'Jena' can be an answer for 'battle' (Jena is an example). I am not sure about the 'napoleonic' bit.
'in mundane journal picked up' is the wordplay.
'in' indicates the answer is hidden within the clue.
'picked up' says the letters should be written in reverse.
'anej' is hidden within 'mundane journal'.
'anej' in reverse letter order is 'JENA'.
'seen' acts as a link.
Can you help me to learn more?
(Other definitions for jena that I've seen before include "Napoleonic victory" , "German town" , "1806 battle where Napoleon routed the Prussians" , "German city" , "town in Thuringia" .)