River scavenger, lad at work in darkness (7)
I believe the answer is:
mudlark
'river scavenger' is the definition.
'mudlark' can be an answer for 'scavenger' (I've seen this before). I'm not certain of the 'river' bit.
'lad at work in darkness' is the wordplay.
'at work' is an anagram indicator.
'in' means one lot of letters goes inside another.
'darkness' becomes 'murk' (I have seen 'Gloomy darkness' mean 'murk' so perhaps 'darkness' could also mean 'murk').
'lad' anagrammed gives 'dla'.
'dla' inserted into 'murk' is 'MUDLARK'.
Can you help me to learn more?
(Other definitions for mudlark that I've seen before include "One scavenging beside river" , "flyer" , "Scavenger" .)