Scattered krone found in second lake dive (7)
I believe the answer is:
snorkel
'dive' is the definition.
(I know this)
'scattered krone found in second lake' is the wordplay.
'scattered' indicates an anagram.
'found in' means one lot of letters goes inside another.
'second' becomes 's' (common abbreviation).
'lake' becomes 'L' (geographical abbreviation).
'krone' with letters rearranged gives 'norke'.
's'+'l'='sl'
'norke' placed inside 'sl' is 'SNORKEL'.
(Other definitions for snorkel that I've seen before include "Swimmer's air tube" , "Bent tube for a swimmer's mouth" , "Breathing aid for a swimmer" , "Diver's breathing tube" , "Surface swimmer's breathing aid" .)