You lovely beaches! So many? (9)
I believe the answer is:
thousands
'so many?' is the definition.
(thousands of something)
'you lovely beaches' is the wordplay.
'you' becomes 'thou' (historical second person pronoun).
'lovely beaches' becomes 'sands' (sands can mean a beach area).
'thou'+'sands'='THOUSANDS'
(Other definitions for thousands that I've seen before include "Crowds" , "Dan shouts out at many hundreds" , "large sum?" , "1000s" , "a lot" .)