Make easy life a tacit arrangement (10)
I believe the answer is:
facilitate
'make easy' is the definition.
(I've seen this before)
'life a tacit arrangement' is the wordplay.
'arrangement' indicates anagramming the letters.
'life'+'a'+'tacit'='lifeatacit'
'lifeatacit' with letters rearranged gives 'FACILITATE'.
(Other definitions for facilitate that I've seen before include "Make easier" , "Ease" , "Make (something) easy" .)