Regarding enemy rising loudly and unmatched (3-3)
I believe the answer is:
one-off
'unmatched' is the definition.
(a one-off is unmatched)
'regarding enemy rising loudly' is the wordplay.
'regarding' becomes 'on' (on or regarding a particular topic).
'enemy' becomes 'foe' (synonyms).
'rising' is a reversal indicator (going up in a down clue).
'loudly' becomes 'f' (short for forte - 'loud' in music).
'foe' written backwards gives 'eof'.
'on'+'eof'+'f'='ONE-OFF'
'and' acts as a link.
(Other definitions for one-off that I've seen before include "Item made once only" , "Made or done as a single thing, not repeated" , "Happening only once" , "Unique person or occurrence" , "A single event, not reproduced or repeated" .)