Seed planted in Armagnac or nearby (5)
I believe the answer is:
acorn
'seed' is the definition.
(I've seen this before)
'planted in armagnac or nearby' is the wordplay.
'planted in' indicates a hidden word.
'ACORN' can be found hidden inside 'armagnac or nearby'.
(Other definitions for acorn that I've seen before include "Tree seed" , "Source of a great oak" , "Fruit of the oak tree" , "From which a tall tree may grow" , "mast" .)