Section of church seeing primate embracing son (4)
I believe the answer is:
apse
'section of church' is the definition.
(I've seen this in other clues)
'primate embracing son' is the wordplay.
'primate' becomes 'ape' (large primate).
'embracing' is an insertion indicator.
'son' becomes 's' (genealogical abbreviation for son).
'ape' placed around 's' is 'APSE'.
'seeing' acts as a link.
(Other definitions for apse that I've seen before include "Church recess with domed or arched roof" , "Architectural feature in a church" , "Peas (anag) - found in church" , "Church's part" , "where praetor sat" .)