Normal (5)
(Other definitions for natural that I've seen before include "An ideal person" , "white key on a piano?" , "Artless, unaffected," , "Unaffected; unaltered" , "Fuel from underground" .)
'normal' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for regular that I've seen before include "Happening frequently" , "fighter" , "Habitui" , "Ordinary" , "Perishes" .)
'normal' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for usual that I've seen before include "Common, normal" , "Common or garden" , "Conventional" , "Unexceptional" , "Ordinary" .)
'normal' is the definition.
(similar in meaning)
This is the entire clue.
(Other definitions for standard that I've seen before include "Criterion, touchstone" , "sort of rose" , "Flag - of the usual kind" , "Level of quality; flag" , "Principle" .)