Public disturbance to support glib nationalist (7)
I believe the answer is:
patriot
'nationalist' is the definition.
(synonyms)
'public disturbance to support glib' is the wordplay.
'public disturbance' becomes 'riot' (I've seen this before).
'to support' says to put letters next to each other (in a down clue, some letters hold others up).
'glib' becomes 'pat' (synonyms).
'riot' after 'pat' is 'PATRIOT'.
(Other definitions for patriot that I've seen before include "One who loves his or her country" , "Defender of country" , "One with a strong love of country" , "Nationalist" , "A lover of fatherland" .)