An afterthought about better instrumentalists
I believe the answer is:
players
'instrumentalists' is the definition.
(I know this)
'an afterthought about better' is the wordplay.
'an afterthought' becomes 'ps' (ps stands for postscript).
'about' indicates putting letters inside.
'better' becomes 'layer' (I can't explain this - if you can you should give a lot more credence to this answer).
'ps' going around 'layer' is 'PLAYERS'.
Can you help me to learn more?
(Other definitions for players that I've seen before include "Actors" , "They participate in games" , "cast" , "Team members" , "Performers" .)