Empty talk in giving assessment (3)
I believe the answer is:
'empty talk' is the definition.
(I've seen this before)
'in giving assessment' is the wordplay.
'in' indicates a hidden word.
'GAS' is hidden in the letters of 'giving assessment'.
(Other definitions for gas that I've seen before include "natural resource" , "Piped fuel" , "could be embarrassing for American" , "Eg, oxygen" , "Hydrogen or methane, say" .)