Sink money wearing formal top (6)
I believe the answer is:
invest
'sink money' is the definition.
'invest' can be an answer for 'sink' (I've seen this before). I am not certain of the 'money' bit.
'wearing formal top' is the wordplay.
'wearing' becomes 'in' (as in being 'in' certain clothes).
'formal top' becomes 'vest' (I've seen this before. I am not sure about the 'formal' bit.).
'in'+'vest'='INVEST'
Can you help me to learn more?
(Other definitions for invest that I've seen before include "Put money into a company" , "Put money into in hopes of a return" , "Lay siege" , "Play the market" , "Lay out in expectation of profit" .)