What remains of passion and honour in hero's heart (5)
I believe the answer is:
ember
'what remains of passion' is the definition.
(as in the flames of passion)
'honour in hero's heart' is the wordplay.
'honour' becomes 'mbe' (Member of the British Empire award).
'in' is an insertion indicator.
'heart' indicates the central letters.
The middle of 'hero' is 'er'.
'mbe' placed inside 'er' is 'EMBER'.
'and' is the link.
(Other definitions for ember that I've seen before include "Burning coal" , "Small piece of glowing coal in a dying fire" , "Material in dying fire" , "Cryptic question" , "Glowing coal; prayer (Days)" .)