There's a lot of you on the beach (9)
I believe the answer is:
thousands
'there's a lot' is the definition.
I can't judge whether this definition defines the answer.
'you on the beach' is the wordplay.
'you' becomes 'thou' (historical second person pronoun).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'the beach' becomes 'sands' (sands can mean a beach area).
'thou'+'sands'='THOUSANDS'
'of' is the link.
Can you help me to learn more?
(Other definitions for thousands that I've seen before include "Crowds" , "Large numbers" , "a lot" , "Dan shouts out at many hundreds" , "1000s" .)