Pieces my boss receives, and what he may do to them? (5)
I believe the answer is:
emend
'what he may do to them?' is the definition.
The definition suggests a singular noun but the answer is not.
'pieces my boss receives' is the wordplay.
'pieces' becomes 'men' (e.g. in chess).
'my boss' becomes 'ed' (abbreviation for editor, the setter's boss).
'receives' means one lot of letters goes inside another (inserted letters are received).
'men' placed inside 'ed' is 'EMEND'.
'and' is the link.
Can you help me to learn more?
(Other definitions for emend that I've seen before include "Improve (texts)" , "get rid of faults" , "Revise (a text) (E, not A)" , "Improve by altering" , "Make correction in written material" .)