Infinite changes sensed involving Left (7)
I believe the answer is:
endless
'infinite' is the definition.
(similar in meaning)
'changes sensed involving left' is the wordplay.
'changes' indicates an anagram.
'involving' is an insertion indicator.
'left' becomes 'l' (common abbreviation).
'sensed' is an anagram of 'endess'.
'endess' going around 'l' is 'ENDLESS'.
(Other definitions for endless that I've seen before include "Occurring so frequently so as to seem uninterrupted" , "Without limit" , "Infinite, perpetual" , "without finishing" , "Unceasing" .)