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'm unsure of the 'mere' bit.
'story about heartless tyrant' is the wordplay.
'story' becomes 'tale' (synonyms).
'about' indicates putting letters inside.
'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)'" .)