Secured new bathing shelters close to shore (2,3,3)
I believe the answer is:
in the bag
'secured' is the definition.
(I've seen this before)
'new bathing shelters close to shore' is the wordplay.
'new' indicates anagramming the letters.
'shelters' means one lot of letters goes inside another.
'close to' says to take the final letters (the close of something is the end).
The last letter of 'shore' is 'e'.
'bathing' with letters rearranged gives 'inthbag'.
'inthbag' placed around 'e' is 'IN THE BAG'.
(Other definitions for in the bag that I've seen before include "almost secured" , "Sacked" , "Virtually secured (informal)" , "that's virtually certain" , "Where mail may be" .)