Forgetfulness of seaman drunk around island (7)
I believe the answer is:
amnesia
'forgetfulness' is the definition.
(I've seen this before)
'seaman drunk around island' is the wordplay.
'drunk' indicates an anagram.
'around' is an insertion indicator.
'island' becomes 'i' (geographical abbreviation).
'seaman' with letters rearranged gives 'amnesa'.
'amnesa' enclosing 'i' is 'AMNESIA'.
'of' is the link.
(Other definitions for amnesia that I've seen before include "Partial or total loss of memory" , "Inability to remember" , "Disorder" , "Complaint" , "Asia men with memory loss (7)" .)