Examine an easy puzzle left inside (7)
I believe the answer is:
analyse
'examine' is the definition.
(synonyms)
'an easy puzzle left inside' is the wordplay.
'puzzle' is an anagram indicator.
'left' becomes 'l' (common abbreviation).
'inside' indicates putting letters inside.
'easy' with letters rearranged gives 'ayse'.
'ayse' placed around 'l' is 'alyse'.
'an'+'alyse'='ANALYSE'
(Other definitions for analyse that I've seen before include "Break down into components parts and examine" , "test" , "Examine and interpret" , "Dissect" , "Examine the component parts" .)