Saintly soup perhaps contains one (5)
I believe the answer is:
pious
'saintly' is the definition.
(I've seen this before)
'soup perhaps contains one' is the wordplay.
'perhaps' is an anagram indicator.
'contains' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'soup' anagrammed gives 'pous'.
'pous' going around 'i' is 'PIOUS'.
(Other definitions for pious that I've seen before include "Sanctimonious" , "God-fearing" , "Dutiful" , "Devout" , "Good" .)