Record leads to Lohengrin's original German libretto (7)
I believe the answer is:
logbook
'record' is the definition.
(logbook is a kind of record)
'leads to lohengrin's original german libretto' is the wordplay.
'leads to' says to take the initial letters.
'libretto' becomes 'book'.
The initial letters of 'lohengrin original german' is 'log'.
'log'+'book'='LOGBOOK'
(Other definitions for logbook that I've seen before include "Former vehicle document" , "Where details of voyages are written" , "Registration paper" , "Incident-recording volume" , "Car owner's document" .)