Has to make professions of loyalty (5)
I believe the answer is:
oaths
'professions of loyalty' is the definition.
(I've seen this before)
'has to make' is the wordplay.
'make' is an anagram indicator.
'has'+'to'='hasto'
'hasto' anagrammed gives 'OATHS'.
(Other definitions for oaths that I've seen before include "Solemn sworn promises" , "Cursing" , "four-letter words" , "Curses - words of honour?" , "Solemn vows" .)