Primarily if distressed individuals occasionally make such expressions (6)
I believe the answer is:
idioms
'expressions' is the definition.
(I know this)
'primarily if distressed individuals occasionally make such' is the wordplay.
'primarily' suggests taking the first letters.
The first letters of 'if distressed individuals occasionally make such' is 'IDIOMS'.
(Other definitions for idioms that I've seen before include "Modes of expression peculiar to a language" , "Dialects, vernaculars" , "Group of words having a meaning not obvious from the words e.g over the moon" , "Sayings as of a people or group" , "styles of speech" .)