Four pairs in old court given notice (5)
I believe the answer is:
octad
'four pairs' is the definition.
'old court given notice' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'court' becomes 'ct' (abbreviation used in road names).
'given' says to put letters next to each other.
'notice' becomes 'ad' (both can mean an advertisement).
'o'+'ct'+'ad'='OCTAD'
'in' acts as a link.
(Other definitions for octad that I've seen before include "E.g. quarterfinalists" , "Group" , "Crew, perhaps" , "quarter-finalists, perhaps" .)