A million pocketed by ruler — tax is high, without boundaries (10)
I believe the answer is:
extramural
'without boundaries' is the definition.
I can't judge whether this defines the answer.
'a million pocketed by ruler tax is high' is the wordplay.
'million' becomes 'm' (abbreviation).
'pocketed by' means one lot of letters goes inside another.
'is high' indicates anagramming the letters (like drunk).
'a'+'m'='am'
'ruler'+'tax'='rulertax'
'rulertax' is an anagram of 'extrural'.
'am' placed into 'extrural' is 'EXTRAMURAL'.
Can you help me to learn more?
(Other definitions for extramural that I've seen before include "outside the university" , "What may be a wide painting" , "Off-premises (univ. studies)" , "outside the building" , "Taking place off campus?" .)