In Marseille we must support erratic goalie, being exaggeratedly complimentary (10)
I believe the answer is:
oleaginous
'exaggeratedly complimentary' is the definition.
I can't tell whether this defines the answer.
'in marseille we must support erratic goalie' is the wordplay.
'in marseille' becomes 'no' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'we' becomes 'us'.
'must support' says to put letters next to each other (in a down clue, some letters go below others).
'erratic' indicates an anagram.
'goalie' with letters rearranged gives 'oleagi'.
'no'+'us'='nous'
'nous' put after 'oleagi' is 'OLEAGINOUS'.
'being' acts as a link.
Can you help me to learn more?
(Other definitions for oleaginous that I've seen before include "oily" , "fawning" .)