Sarah giving a speech to relish (5,8)
I believe the answer is:
salad dressing
'relish' is the definition.
(type of sauce or relish)
'sarah giving a speech to' is the wordplay.
'sarah' becomes 'Sal' (Sally is a common pet form of Sarah).
'giving a speech to' becomes 'addressing' ('address' can be a synonym of 'give a speech to').
'sal'+'addressing'='SALAD-DRESSING'
(Other definitions for salad dressing that I've seen before include "sauce" , "leaves having taken this coat?" , "Eg, Thousand Island or French" , "saucy thing!" , "what goes on rocket?" .)