Sort of therapy necessitating major outlay? (6)
I believe the answer is:
retail
'outlay?' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe they are linked in a way I don't understand?
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for retail that I've seen before include "This trade serves the general public" , "This trade sells direct to the public" , "Sale of goods individually" , "Trade selling goods to the general public" , "Form of sales" .)