Calms down, adjusting last pace (8)
I believe the answer is:
placates
'calms down' is the definition.
(placating is a kind of calming down)
'adjusting last pace' is the wordplay.
'adjusting' indicates anagramming the letters.
'last'+'pace'='lastpace'
'lastpace' is an anagram of 'PLACATES'.
(Other definitions for placates that I've seen before include "Assuages" , "Calms down" , "'Appeases, mollifies (8)'" .)