Resolute holy person, head, failing to start, then period abstaining from food (9)
I believe the answer is:
steadfast
'resolute' is the definition.
(similar in meaning)
'holy person head failing to start then period abstaining from food' is the wordplay.
I cannot quite understand how this works, but
'period' could be 'ad' (AD is an example) and 'ad' is located in the answer.
'food' could be 'e' (E is an example) and 'e' is found in the answer.
'holy person' could be 'st' (short for saint) and 'st' is found within the answer.
The remaining letters 'fast' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for steadfast that I've seen before include "Firm and unwavering" , "Fixed, unyielding" , "Resolute, unwavering" , "stable" , "Constant, not changing or yielding" .)