Regret moving on from Rouen (3)
I believe the answer is:
rue
'regret moving' is the definition.
'rue' can be an answer for 'regret' (to rue something is to regret it). I'm not certain of the 'moving' bit.
'on from rouen' is the wordplay.
'from' indicates named letters should be taken away.
'rouen' with 'on' removed is 'RUE'.
Can you help me to learn more?
(Other definitions for rue that I've seen before include "Regret, be sorry for" , "show you're sorry!" , "Lament; a herb" , "Plant producing oil" , "Bemoan" .)