Starts to plan attack with knight, or other chess piece (4)
I believe the answer is:
pawn
'chess piece' is the definition.
(I know that pawn is a type of chess piece)
'starts to plan attack with knight' is the wordplay.
'starts to' indicates taking the first letters.
'knight' becomes 'n' (chess abbreviation).
The initial letters of 'plan attack with' is 'paw'.
'paw'+'n'='PAWN'
'or other' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for pawn that I've seen before include "Person one used" , "piece on board" , "Chess piece -- puppet" , "Man of lowest value" , "Part with temporarily to raise money" .)