Special preserve of former prince in time married (5,3)

I believe the answer is:
extra jam
'special preserve' is the definition.
'extra jam' can be an answer for 'preserve'. I'm not sure about the 'special' bit.
'former prince in time married' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'prince' becomes 'raja' (I've seen this in another clue).
'in' indicates putting letters inside.
'time' becomes 't' (abbreviation).
'married' becomes 'm' (abbreviation, e.g. in genealogy).
't'+'m'='tm'
'raja' placed into 'tm' is 'trajam'.
'ex'+'trajam'='EXTRA JAM'
'of' is the link.
Can you help me to learn more?
(Another definition for extra jam that I've seen is " Preserve following regulation".)
