Was a killer left to go in all directions bar north? (4)
I believe the answer is:
slew
'was a killer' is the definition.
(past tense of 'slay')
'left to go in all directions bar north?' is the wordplay.
'left' becomes 'l' (common abbreviation).
'to go in' means one lot of letters goes inside another.
'all directions bar' becomes 'wes' (I can't justify this - if you can you should believe this answer much more).
'north?' is a reversal indicator (in a down clue, letters go up or 'north').
'l' going inside 'wes' is 'wels'.
'wels' reversed gives 'SLEW'.
Can you help me to learn more?
(Other definitions for slew that I've seen before include "Slaughtered" , "Turn uncontrollably" , "Killed in literary manner" , "Violently killed" , "murdered" .)