Trick a Nile region student concerned with marriage (9)
I believe the answer is:
connubial
'concerned with marriage' is the definition.
I can't tell whether this definition defines the answer.
'trick a nile region student' is the wordplay.
'trick' becomes 'con' (a con is a fraud or trick).
'a nile region' becomes 'nubia' (I can't explain this - if you can you should give a lot more credence to this answer).
'student' becomes 'l' (as in L-plates for learner drivers).
'con'+'nubia'+'l'='CONNUBIAL'
Can you help me to learn more?
(Other definitions for connubial that I've seen before include "This bliss is of the married sort" , "Relating to marriage" , "Of relationship between husband and wife" .)