Passed one letter, then two (6)
I believe the answer is:
handed
'passed' is the definition.
('hand' can be a synonym of 'pass')
'one letter then two' is the wordplay.
I cannot really see how this works, but
'one' could be 'an' (an apple is one apple) and 'an' is present in the answer.
'letter' could be 'h' and 'h' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for handed that I've seen before include "Incontrovertible" , "given" .)