Gruesome mass needs a bishop to inscribe tract (7)
I believe the answer is:
macabre
'gruesome' is the definition.
(synonyms)
'mass needs a bishop to inscribe tract' is the wordplay.
I cannot really see how this works, but
'mass' could be 'm' (symbol used in Physics e.g. f=ma) and 'm' is found in the answer.
'a' is within the answer.
'bishop' could be 'b' (abbreviation used in chess) and 'b' is located in the answer.
The remaining letters 'care' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for macabre that I've seen before include "Gruesome, suggesting death" , "Gruesome and weird" , "Gruesome, morbid" , "Ghastly, gruesome" , "Brace ma, being gruesome" .)