Place might somehow become calm (10)
I believe the answer is:
phlegmatic
'calm' is the definition.
(I've seen this before)
'place might somehow' is the wordplay.
'somehow' is an anagram indicator.
'place'+'might'='placemight'
'placemight' with letters rearranged gives 'PHLEGMATIC'.
'become' is the link.
(Other definitions for phlegmatic that I've seen before include "cool" , "Unexcitable" , "Unemotional" , "dull and lifeless" , "Calm; philosophical" .)