Tops at leaving swell functions (7)
I believe the answer is:
blouses
'tops' is the definition.
(blouse is a kind of top)
'leaving swell functions' is the wordplay.
I cannot really understand how this works, but
'functions' could be 'uses' ('use' can be a synonym of 'function') and 'uses' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'at' acts as a link.
Can you help me to learn more?
(Other definitions for blouses that I've seen before include "Ladies' tops" , "Female garments" .)