Increased power around river nearer the mountains (8)
I believe the answer is:
upstream
'nearer the mountains' is the definition.
I can't tell whether this defines the answer.
'increased power around river' is the wordplay.
'increased' becomes 'up' (something that's up has increased or risen).
'power' becomes 'steam' (I've seen this before).
'around' is an insertion indicator.
'river' becomes 'r' (abbreviation).
'steam' placed around 'r' is 'stream'.
'up'+'stream'='UPSTREAM'
Can you help me to learn more?
(Other definitions for upstream that I've seen before include "Ma erupts (anag.)" , "Towards (river's) source" , "Against a river current" , "Eats rump (anag)" , "Current trend is not" .)