Stock market activity performed under the table (7)
I believe the answer is:
footsie
'stock' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see an association between them that I can't see?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for footsie that I've seen before include "[EXCHANGE] under the table" , "shows city values" , "London Stock Exchange share index (informal)" , "Flirting style" , "FT index -- flirty under-the-table play" .)