Principle (5)
(Other definitions for plain that I've seen before include "Unembellished" , "not attractive" , "Treeless expanse" , "open country" , "Simple, unadorned" .)
(Other definitions for right that I've seen before include "Fit" , "Correct; political wing" , "Correct; entitlement" , "Morally defensible" , "Not left" .)
(Other definitions for exact that I've seen before include "19 [WREST]" , "Precise, accurate" , "Specific" , "Demand, extort" , "Force out" .)
(Other definitions for close that I've seen before include "Near - conclusion" , "Not far off" , "Heavy" , "Imminent" , "Cathedral's precincts" .)
(Other definitions for whole that I've seen before include "Total" , "undamaged" , "Entire, undivided" , "Integral" , "In entirety" .)
(Other definitions for pukka that I've seen before include "Absolutely first class and genuine" , "High-class - permanent" , "(In 5) the real McCoy" , "that's for sure" , "not mock" .)
'principle' is the definition.
(a tenet is a principle or value)
This is all the clue.
(Other definitions for tenet that I've seen before include "you may believe in it" , "Teaching" , "Article of belief" , "Rule" , "A religious doctrine proclaimed as true without proof" .)
(Other definitions for licit that I've seen before include "Not forbidden, lawful" , "Permissible" , "Legitimate" , "not banned" , "Within the law" .)
(Other definitions for usual that I've seen before include "Normally done" , "Ordinary" , "Drink repeatedly taken" , "not rum?" , "Standard" .)
'principle' is the definition.
(I know that ethic is a type of principle)
This is the entire clue.
(Other definitions for ethic that I've seen before include "Moral code" , "Moral value" , "Set of moral principles" , "Moral rule" , "An unusual factor in morals" .)
'principle' is the definition.
(I know that dogma is a type of principle)
This is all the clue.
(Other definitions for dogma that I've seen before include "A religious belief" , "church teaching" , "Fixed belief" , "Body of religious doctrine" , "Incontrovertible set of principles" .)
(Other definitions for valid that I've seen before include "Legally acceptable and sound" , "Effectual" , "Legally accepted or logical" , "Legitimate" , "Well-grounded" .)
(Other definitions for legit that I've seen before include "Such theatre" , "Briefly in accordance with law or rules" , "Above board (abbr)" , "Reliable" , "not unlawful" .)
(Other definitions for sound that I've seen before include "note, for instance" , "Fit" , "Unimpaired" , "Speaking" , "Not diseased or damaged - listen" .)
'principle' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for axiom that I've seen before include "truthful statement" , "Fundamental proposition" , "Obviously true statement" , "that's self-evident" , "A saying that's widely accepted as true" .)