Identify problem of floundering dog in sea (8)
I believe the answer is:
diagnose
'identify problem' is the definition.
(as in diagnosing a medical problem)
'floundering dog in sea' is the wordplay.
'floundering' is an anagram indicator (I've seen this in other clues).
'dog'+'in'+'sea'='doginsea'
'doginsea' with letters rearranged gives 'DIAGNOSE'.
'of' is the link.
(Other definitions for diagnose that I've seen before include "Identify (an illness)" , "Analyse medically" , "Identify a disease from its symptoms" , "Analyse a problem" , "Ascertain cause of illness in San Diego" .)