Unwelcome adviser supports European at club (4-4,6)
I believe the answer is:
back-seat driver
'unwelcome adviser' is the definition.
(passenger offering unwanted advice to a driver)
'supports european at club' is the wordplay.
I cannot quite understand how this works, but
'supports' could be 'backs' (backing is a kind of supporting) and 'backs' is present in the answer.
'european' could be 'e' (abbreviation e.g. EU) and 'e' is found within the answer.
'at' is present in the answer.
'club' could be 'driver' (type of golf club) and 'driver' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for back-seat driver that I've seen is " one offering advice".)