By getting a blockhead out of a hellish hole (5)
I believe the answer is:
abyss
'hellish hole' is the definition.
'abyss' can be an answer for 'hole' (I have seen 'Deep hole ' mean 'abyss' so perhaps 'hole' could also mean 'abyss'). I'm unsure of the 'hellish' bit.
'by getting a blockhead out of a' is the wordplay.
'getting' means one lot of letters go next to another.
'blockhead' becomes 'ass' (I've seen this in another clue).
'out of' indicates named letters should be taken away.
'ass' with 'a' taken out is 'ss'.
'by' after 'a' is 'aby'.
'aby'+'ss'='ABYSS'
Can you help me to learn more?
(Other definitions for abyss that I've seen before include "canyon?" , "something rather deep" , "deep depression" , "crevasse" , "Seemingly bottomless chasm" .)