Protestors' slogan isn't able to overcome harsh chief (5)
I believe the answer is:
chant
'protestors' slogan' is the definition.
I can't judge whether this definition defines the answer.
'isn't able to overcome harsh chief' is the wordplay.
'isn't able' becomes 'can't' (I've seen this in another clue).
'to overcome' means one lot of letters goes inside another (some letters come over or go around others).
'chief' suggests taking the first letters (the letter which leads the word).
The first letter of 'harsh' is 'h'.
'cant' placed around 'h' is 'CHANT'.
Can you help me to learn more?
(Other definitions for chant that I've seen before include "Type of singing with a simple melody and several words sung on one note" , "Type of group singing" , "Repeated rhythmic song" , "Intone (psalm)" , "Repeated rhythmic phrase" .)