Significance of delay in speech (6)
I believe the answer is:
weight
'significance' is the definition.
(thesaurus)
'delay in speech' is the wordplay.
'delay' becomes 'wait' ('wait' can be a synonym of 'delay').
'in speech' shows a homophone (sound like).
'wait' sounds like 'WEIGHT'.
'of' is the link.
(Other definitions for weight that I've seen before include "Heavy object" , "Import" , "Gravitational pull" , "Heavy load - preponderance" , "gives a sense of oppression" .)