Deal a hail trapping pieces (9)
I believe the answer is:
agreement
'deal' is the definition.
(I know that deal can be written as agreement)
'a hail trapping pieces' is the wordplay.
'hail' becomes 'greet' (I've seen this in another clue).
'trapping' means one lot of letters goes inside another.
'pieces' becomes 'men' (man can mean a chess piece).
'greet' enclosing 'men' is 'greement'.
'a'+'greement'='AGREEMENT'
(Other definitions for agreement that I've seen before include "Compact, accord" , "Unlikely result" , "Harmony of opinion" , "Accord, contract" , "Conformity" .)