Marmalade, perhaps, Paddington's opening with reticence (8)
I believe the answer is:
preserve
'marmalade' is the definition.
(I've seen this in another clue)
'paddington's opening with reticence' is the wordplay.
'opening' suggests taking the first letters.
'with' says to put letters next to each other.
'reticence' becomes 're-serve' (synonyms).
The first letter of 'paddington' is 'p'.
'p'+'reserve'='PRESERVE'
'perhaps' is the link.
(Other definitions for preserve that I've seen before include "Maintain - jam" , "Maintain; keep safe" , "Area of activity" , "Guard" , "Jam; safeguard" .)