Advance, nearly losing knight (5)
I believe the answer is:
early
'advance' is the definition.
(similar in meaning)
'nearly losing knight' is the wordplay.
'losing' indicates named letters should be taken away.
'knight' becomes 'n' (chess abbreviation).
'nearly' with 'n' taken away is 'EARLY'.
(Other definitions for early that I've seen before include "and 26: Too soon to be sure" , "Ahead of schedule" , "sooner than expected" , "Before the ETA" , "near beginning" .)