One looking after currency: Darling, second to Brown (9)
I believe the answer is:
treasured
'one looking after currency darling' is the definition.
'treasured' can be an answer for 'darling' (I've seen this before). I'm unsure of the 'one looking after currency' bit.
'second to brown' is the wordplay.
I cannot really understand how this works, but
'second' could be 're' (prefix meaning second in eg review, re-education) and 're' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for treasured that I've seen before include "Cherished, held dear" , "Much-valued" , "Prized, precious" , "Darling" , "Loved" .)