Lecture is encouraging on war I roughly intervened (10)
I believe the answer is:
earwigging
'lecture' is the definition.
(both can mean a reprimand or telling off)
'encouraging on war i roughly intervened' is the wordplay.
'encouraging on' becomes 'egging' (to egg on is to encourage).
'roughly' indicates anagramming the letters.
'intervened' means one lot of letters goes inside another.
'war'+'i'='wari'
'wari' anagrammed gives 'arwi'.
'egging' going around 'arwi' is 'EARWIGGING'.
'is' is the link.
(Other definitions for earwigging that I've seen before include "Listening" , "Eavesdropping (colloq.)" .)