A reminder to get money (4)
I believe the answer is:
note
This clue is a double definition.
'a reminder' is the first definition.
(thesaurus)
'money' is the second definition.
(thesaurus)
'to get' is the link.
(Other definitions for note that I've seen before include "Eg, fiver; annotation" , "Mark - sound - money" , "Crotchet or minim, perhaps" , "Some money - some music" , "A, B or C, for example - short message" .)