Story about heartless tyrant is mere gossip (6)
I believe the answer is:
tattle
'mere gossip' is the definition.
'tattle' can be an answer for 'gossip' (I've seen this before). I am not certain of the 'mere' bit.
'story about heartless tyrant' is the wordplay.
'story' becomes 'tale' (synonyms).
'about' is an insertion indicator.
'heartless' means to remove the middle letters.
'tyrant' with its middle removed is 'tt'.
'tale' enclosing 'tt' is 'TATTLE'.
'is' is the link.
Can you help me to learn more?
(Other definitions for tattle that I've seen before include "Tell tales" , "Chatter idly" , "Divulge secrets" , "Inform on someone" , "'Gossip, idle talk (6)'" .)