First? Almost not the first (5)
I believe the answer is:
early
'first?' is the definition.
('early' is associated in meaning with 'first')
'almost not the first' is the wordplay.
'almost' becomes 'nearly' ('nearly' can be a synonym of 'almost').
'not the first' means to remove the first letter.
'nearly' with its first letter taken off is 'EARLY'.
(Other definitions for early that I've seen before include "Type of bird" , "New-season" , "Untimely" , "Before appointed time" , "In good time" .)