European lightweight absorbing sanctimonious maxim (7)
I believe the answer is:
epigram
'maxim' is the definition.
(thesaurus)
'european lightweight absorbing sanctimonious' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'lightweight' becomes 'gram'.
'absorbing' is an insertion indicator.
'sanctimonious' becomes 'pi'.
'e'+'gram'='egram'
'egram' placed around 'pi' is 'EPIGRAM'.
(Other definitions for epigram that I've seen before include "A clever witty saying" , "Witty poem" , "Brief witty saying" , "Short, memorable saying" , "Brief witticism" .)