One admiral at sea a regular record keeper (6,4)
I believe the answer is:
adrian mole
'a regular record keeper' is the definition.
(fictional diary keeper in books by Sue Townsend)
'one admiral at sea' is the wordplay.
'at sea' indicates anagramming the letters.
'one'+'admiral'='oneadmiral'
'oneadmiral' anagrammed gives 'ADRIAN MOLE'.
(Other definitions for adrian mole that I've seen before include "diarist" , "Fictional teenage diary-keeper" , "Young journalist" .)