Bad blood between Meg Thatcher and the revolutionary (6)
I believe the answer is:
hatred
'bad blood between meg' is the definition.
I can't tell whether this defines the answer.
'thatcher and the revolutionary' is the wordplay.
'thatcher' becomes 'hat' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'and' means one lot of letters go next to another.
'the revolutionary' becomes 'red'.
'hat'+'red'='HATRED'
Can you help me to learn more?
(Other definitions for hatred that I've seen before include "Great dislike" , "Intense dislike" , "Deep dislike and aversion" , "Violent emotion" , "Animus" .)