Nurse extremely likely to be like a sibling (8)
I believe the answer is:
sisterly
'be like a sibling' is the definition.
I can't tell whether this definition defines the answer.
'nurse extremely likely' is the wordplay.
'nurse' becomes 'sister' (a female nurse might be called sister).
'extremely' means to remove the middle letters (only the extremes of the word are used).
'likely' with its middle removed is 'ly'.
'sister'+'ly'='SISTERLY'
'to' is the link.
Can you help me to learn more?
(Other definitions for sisterly that I've seen before include "Friendly in a female way" , "The counterpart of brotherly" , "Like a female relative" , "To do with one's female sibling" , "I try less (anag.)" .)