Back to render a composition (4,3)
I believe the answer is:
rear end
'back' is the definition.
(thesaurus)
'render a composition' is the wordplay.
'composition' indicates an anagram.
'render'+'a'='rendera'
'rendera' is an anagram of 'REAR-END'.
'to' is the link.
(Other definitions for rear end that I've seen before include "run into the car in front" , "Run into another vehicle from behind" , "seat" , "Buttocks (informal)" , "The buttocks (colloq.)" .)