Sixty engineers stopping a source of excitement on match day (10)
I believe the answer is:
threescore
'sixty' is the definition.
(synonyms)
'engineers stopping a source of excitement on match day' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'stopping' is an insertion indicator (stopping can mean blocking a gap).
'a source of excitement on match day' becomes 'thescore' (I can't explain this - if you can you should give a lot more credence to this answer).
're' put within 'thescore' is 'THREESCORE'.
Can you help me to learn more?
(Another definition for threescore that I've seen is " Sixty".)