Sibling embraces one with spirit (4)
I believe the answer is:
brio
'spirit' is the definition.
(I've seen this in another clue)
'sibling embraces one' is the wordplay.
'sibling' becomes 'bro' (I've seen this before).
'embraces' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'bro' enclosing 'i' is 'BRIO'.
'with' acts as a link.
(Other definitions for brio that I've seen before include "Vivacity of style" , "'Con ..., musically with vigour (4)'" , "'Liveliness, vivacity (4)'" , "Vigour (in music)" , "Dash or verve, from Italian" .)