Records office, say, is to attempt tracking source of records (8)
I believe the answer is:
registry
'records office' is the definition.
(I've seen this before)
'say is to attempt tracking source of records' is the wordplay.
'say' becomes 'eg'.
'to attempt' becomes 'try' (synonyms).
'tracking' says to put letters next to each other (track can mean to follow or go after).
'source of' indicates taking the first letters.
The first letter of 'records' is 'r'.
'eg'+'is'+'try'='egistry'
'egistry' put after 'r' is 'REGISTRY'.
(Other definitions for registry that I've seen before include "Office where records are kept" , "Official written record of names, events etc" , "where files may be observed" , "Place to keep records" , "Place of record" .)