Loud note played outside regularly (5)
I believe the answer is:
often
'regularly' is the definition.
(thesaurus)
'loud note played outside' is the wordplay.
'loud' becomes 'f' (A musical term).
'played' indicates an anagram.
'outside' means one lot of letters goes inside another.
'note' anagrammed gives 'oten'.
'f' going within 'oten' is 'OFTEN'.
(Other definitions for often that I've seen before include "Frequently, not seldom" , "Repeatedly with regularity" , "Commonly" , "A great deal" , "More than occasionally" .)