Train wrongly, I notice, carrying gold coin on motorway (10)
I believe the answer is:
miseducate
'train wrongly' is the definition.
(train or educate the wrong way)
'i notice carrying gold coin on motorway' is the wordplay.
'notice' becomes 'see' (notice can mean to spot or see).
'carrying' means one lot of letters goes inside another.
'gold coin' becomes 'ducat' (historical coin of Europe).
'on' means one lot of letters go next to another.
'motorway' becomes 'M' (as in motorway names - M1, M4 etc).
'see' enclosing 'ducat' is 'seducate'.
'i'+'seducate'='iseducate'
'iseducate' put after 'm' is 'MISEDUCATE'.
(Another definition for miseducate that I've seen is " Fail as teacher".)