River's origin lies in current near the equator (8)
I believe the answer is:
tropical
'river's origin lies' is the definition.
I can't judge whether this defines the answer.
'in current near the equator' is the wordplay.
'in' indicates putting letters inside.
'current' becomes 'topical' (similar in meaning).
'near the equator' becomes 'r' (I can't justify this - if you can you should give a lot more credence to this answer).
'topical' enclosing 'r' is 'TROPICAL'.
Can you help me to learn more?
(Other definitions for tropical that I've seen before include "Hot and humid type of weather" , "Belonging to hot regions" , "Relating to very warm areas" , "Middle-earth" , "extremely warm" .)