Too young for nude swimming craze (8)
I believe the answer is:
underage
'too young' is the definition.
(I've seen this before)
'nude swimming craze' is the wordplay.
'swimming' is an anagram indicator.
'craze' becomes 'rage' ('rage' can be a synonym of 'craze').
'nude' is an anagram of 'unde'.
'unde'+'rage'='UNDERAGE'
'for' is the link.
(Other definitions for underage that I've seen before include "Not old enough to exercise legal right" , "one too young" , "Too tender" , "Not legally old enough" , "Need a rug (anag.)" .)