Considering revision of grade during call (9)
I believe the answer is:
regarding
'considering' is the definition.
('regard' can be a synonym of 'consider')
'revision of grade during call' is the wordplay.
'revision of' indicates anagramming the letters.
'during' is an insertion indicator.
'call' becomes 'ring' ('ring' can be a synonym of 'call'**).
'grade' is an anagram of 'egard'.
'egard' inserted inside 'ring' is 'REGARDING'.
(Other definitions for regarding that I've seen before include "Thinking" , "Concerned with" , "Gazing" , "Concerning" , "Seeing" .)