Secure grade, almost (3)
I believe the answer is:
tie
'secure' is the definition.
(I've seen this before)
'grade almost' is the wordplay.
'grade' becomes 'tier' ('tier' can be a synonym of 'grade').
'almost' means to remove the last letter (most of the word but not all of it).
'tier' with its last letter taken off is 'TIE'.
(Other definitions for tie that I've seen before include "'Fasten, with string say (3)'" , "may make one hot under the collar" , "Bond; draw" , "Neckpiece" , "Almost level" .)