Understanding a key file (5)

I believe the answer is:

grasp

'understanding' is the definition.
(I know that grasp is a type of understanding)

'a key file' is the wordplay.
'a key' becomes 'g' (musical key).
'file' becomes 'rasp' (rasp is a kind of file).
'g'+'rasp'='GRASP'

(Other definitions for grasp that I've seen before include "Seize - comprehend" , "Understand (the point)" , "Understand; take in hand" , "Take firm hold" , "Appreciation" .)

I've seen this clue in The Globe and Mail.

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