Married expert provides spice (4)
I believe the answer is:
mace
'spice' is the definition.
(mace is a kind of spice)
'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'
'provides' is the link.
(Other definitions for mace that I've seen before include "Ceremonial staff or kind of spice" , "Staff of office for a flavouring" , "Tear gas - spice" , "put on the rack?" , "Staff - ground nutmeg" .)