Plays idly, taking first of these firearms (7)
I believe the answer is:
trifles
'plays' is the definition.
(I know this)
'first of these firearms' is the wordplay.
'first of these' becomes 't' (1st letter of 'these').
'firearms' becomes 'rifles' (rifle is a kind of firearm).
't'+'rifles'='TRIFLES'
'idly taking' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for trifles that I've seen before include "Behaves frivolously for popular desserts" , "Toys" .)