Duty to share heart with husband (5)
I believe the answer is:
chore
'duty' is the definition.
(I know that chore is a type of duty)
'heart with husband' is the wordplay.
'heart' becomes 'core' (synonyms).
'with' means one lot of letters goes inside another.
'husband' becomes 'h' (abbreviation).
'core' placed around 'h' is 'CHORE'.
'to share' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for chore that I've seen before include "Household job" , "Unpleasant task" , "easy option? Not so!" , "Onerous task" , "Drudgery" .)