Shifty liar suppressing corrupt urge -- resistance is wavering (9)
I believe the answer is:
irregular
'is wavering' is the definition.
(thesaurus)
'shifty liar suppressing corrupt urge resistance' is the wordplay.
'shifty' is an anagram indicator.
'suppressing' is an insertion indicator.
'corrupt' indicates an anagram.
'resistance' becomes 'r' (abbreviation**).
'liar' with letters rearranged gives 'irla'.
'urge' anagrammed gives 'regu'.
'irla' enclosing 'regu' is 'irregula'.
'irregula'+'r'='IRREGULAR'
(Other definitions for irregular that I've seen before include "Not uniform" , "unprincipled" , "unlike full-time soldiers" , "Unconventional" , "member of the Baker Street contingent" .)