A letter I had tucked away (3)

I believe the answer is:

hid

'tucked away' is the definition.
(I've seen this in another clue)

'a letter i had' is the wordplay.
'a letter' becomes 'h' ().
'i had' becomes 'i'd' (I'd).
'h'+'id'='HID'

(Other definitions for hid that I've seen before include "Remained out of sight" , "wanted to be sought?" , "Stayed out of sight" , "Took cover" , "Shrouded" .)

I've seen this clue in the Evening Standard.

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