'Little river' one will present here (4)
I believe the answer is:
rill
'present here' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'little river one will' is the wordplay.
'little river' becomes 'r'.
'one will' becomes 'I'll' (contraction of 'I will').
'r'+'ill'='RILL'
(Other definitions for rill that I've seen before include "Small brook" , "Brooklet" , "Burn" , "Flowing water" , "Flow of water" .)