Being very firm — or cracking? (10)
I believe the answer is:
resolution
I believe this is a double definition.
'being very firm' is the first definition.
(being resolved or firm)
'cracking?' is the second definition.
(thesaurus)
'or' acts as a link.
(Other definitions for resolution that I've seen before include "Clarifying" , "Firmness - outcome of decision making" , "Firm decision" , "sorting out of problem" , "Verdict" .)