Initial of mine on gold watch for author John (8)
I believe the answer is:
mortimer
'author john' is the definition.
(novelist John Mortimer, 1923-2009)
'initial of mine on gold watch' is the wordplay.
'initial of' indicates taking the first letters (I've seen 'initials' mean this).
'on' is a charade indicator (letters next to each other).
'gold' becomes 'or' ('or' is the heraldic name for gold).
'watch' becomes 'timer' (a watch might be used to time something).
The initial letter of 'mine' is 'm'.
'm'+'or'+'timer'='MORTIMER'
'for' is the link.
(Other definitions for mortimer that I've seen before include "Lawyer who wrote plays" , "- Wheeler, English archaeologist" .)