Where bishop might have to move quickly, sermons about five hundred seconds (5,5)
I believe the answer is:
speed chess
'where bishop might have to move quickly' is the definition.
The definition suggests a singular noun which matches the answer.
'sermons about five hundred seconds' is the wordplay.
'sermons' becomes 'speeches' (I can't explain this - if you can you should give a lot more credence to this answer).
'about' means one lot of letters goes inside another.
'five hundred' becomes 'd' (Roman numeral for c00).
'seconds' becomes 's' (abbreviation).
'speeches' going around 'd' is 'speedches'.
'speedches'+'s'='SPEED CHESS'
Can you help me to learn more?
(Other definitions for speed chess that I've seen before include "attempt to mate quickly" , "which leaves little time for mate" , "movement of men with expedition" .)