Crack within range could be chef's warning (3,4)
I believe the answer is:
pot shot
'be chef's warning' is the definition.
The definition suggests a singular noun which matches the answer.
'crack within range' is the wordplay.
I cannot quite see how this works, but
'crack' could be 'shot' (synonyms) and 'shot' is found in the answer.
The remaining letters 'pot' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'could' is the link.
Can you help me to learn more?
(Other definitions for pot shot that I've seen before include "Ill-considered criticism" , "Casual or random firing attempt" , "Attempt to hit an easy target" , "Casual discharge of bullet" , "Critical remark" .)