Leader missed a typo ultimately within heading (7)
I believe the answer is:
caption
'heading' is the definition.
(I know that caption is a type of title)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for caption that I've seen before include "Pontiac (anag)" , "Text under photo" , "Provide (a picture) with a title" , "Elegance of dress" , "Explanation of an illustration" .)