Discus, say, happening to get filed away first (5,5)
I believe the answer is:
field event
'discus say' is the definition.
(discus is a kind of field event)
'happening to get filed away first' is the wordplay.
I cannot really understand how this works, but
'happening' could be 'even' (I've seen this in another clue) and 'even' is found in the answer.
an anagram of 'filed' is 'field' which is within the answer.
A single letter 't' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for field event that I've seen before include "the javelin, say" , "hammer, say" , "Perhaps shot put" , "contest" .)