Unusual gripe in the morning? That's saying (7)
I believe the answer is:
epigram
'saying' is the definition.
(I've seen this before)
'unusual gripe in the morning?' is the wordplay.
'unusual' indicates an anagram.
'in the morning?' becomes 'am'.
'gripe' anagrammed gives 'epigr'.
'epigr'+'am'='EPIGRAM'
'that's' acts as a link.
(Other definitions for epigram that I've seen before include "witty comment" , "it might be natural to wag" , "Clever remark" , "Concise witty saying" , "Bon mot" .)