Protest line is hard to break apart (8)
I believe the answer is:
demolish
'break apart' is the definition.
'demolish' can be an answer for 'break' (thesaurus). I'm not sure about the 'apart' bit.
'protest line is hard' is the wordplay.
'protest' becomes 'demo' (demonstration).
'line' becomes 'l' (used when specifying particular lines from a poem).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'demo'+'l'+'is'+'h'='DEMOLISH'
'to' is the link.
Can you help me to learn more?
(Other definitions for demolish that I've seen before include "Knock down, a building or argument perhaps" , "Knock down, say a building" , "Break down" , "Eat up" , "Raze to the ground" .)