Fuss by half-hearted mob is precious (8)
I believe the answer is:
adorable
'precious' is the definition.
(I've seen this in another clue)
'fuss by half-hearted mob' is the wordplay.
I cannot quite see how this works, but
'fuss' could be 'ado' (synonyms) and 'ado' is found within the answer.
This may be the basis of clue (or it may be nonsense).
'is' is the link.
(Other definitions for adorable that I've seen before include "Inspiring love" , "Endearing" , "worthy of love" , "Very charming and attractive" , "Worthy of worship" .)