Actually it's more than a little brook (4)
I believe the answer is:
ebro
'actually it's more than a' is the definition.
I can't judge whether this defines the answer.
'little brook' is the wordplay.
'EBRO' is hidden in amongst the letters.
But, I am not sure how this is indicated.
Can you help me to learn more?
(Other definitions for ebro that I've seen before include "that's streaming in Spain?" , "Iberian river" , "foreign river" , "Border Hannibal crossed" , "River of northeast Spain" .)