Holy figureheads transformed into Spartans (6,6)
I believe the answer is:
patron saints
'holy figureheads' is the definition.
(patron saints are holy figures)
'transformed into spartans' is the wordplay.
'transformed' indicates anagramming the letters.
'into'+'spartans'='intospartans'
'intospartans' is an anagram of 'PATRON SAINTS'.
(Other definitions for patron saints that I've seen before include "Very good guides" , "country heroes" .)