Married expert produces old weapon (4)
I believe the answer is:
mace
'old weapon' is the definition.
(I've seen this in another clue)
'married expert' is the wordplay.
'married' becomes 'm' (abbreviation, e.g. in genealogy).
'expert' becomes 'ace' (ace can informally mean very good).
'm'+'ace'='MACE'
'produces' is the link.
(Other definitions for mace that I've seen before include "Staff of office for a flavouring" , "Staff of office and a spice" , "Staff - ground nutmeg" , "Tear gas - spice" , "Spice; heavy club" .)