More tempestuous, making more stir (8)
I believe the answer is:
stormier
'more tempestuous' is the definition.
('stormy' can be similar in meaning to 'tempestuous')
'making more stir' is the wordplay.
'making' is an anagram indicator.
'more'+'stir'='morestir'
'morestir' is an anagram of 'STORMIER'.
(Other definitions for stormier that I've seen before include "More turbulent and tempestuous" , "Having worse weather" .)