Bit of corn by gospel label (7)
I believe the answer is:
earmark
'label' is the definition.
(thesaurus)
'bit of corn by gospel' is the wordplay.
'bit of corn' becomes 'ear' ('ear' is part of 'corn').
'by' says to put letters next to each other.
'gospel' becomes 'Mark' (book of the New Testament).
'ear'+'mark'='EARMARK'
(Other definitions for earmark that I've seen before include "It identifies the outcome" , "'Reserve, set aside (7)'" , "Set aside for future use" , "Reserve for later use" , "Set aside, designate" .)