A lot of quiet, clear swimming (6)
I believe the answer is:
parcel
'a lot' is the definition.
(can mean a bunch or load of something)
'quiet clear swimming' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'swimming' indicates anagramming the letters (letters swim around into a new order).
'clear' anagrammed gives 'arcel'.
'p'+'arcel'='PARCEL'
'of' acts as a link.
(Other definitions for parcel that I've seen before include "Soft shade; crayon" , "Wrapped container" , "plot" , "One wrapped" , "One conveyed" .)