Take cover from the militia leader as killing starts (4)
I believe the answer is:
mask
'take cover' is the definition.
'mask' can be an answer for 'cover' (I've seen this in another clue). I'm unsure of the 'take' bit.
'the militia leader as killing starts' is the wordplay.
'leader' says to take the initial letters.
'starts' suggests taking the first letters.
The initial letter of 'militia' is 'm'.
The initial letter of 'killing' is 'k'.
'm'+'as'+'k'='MASK'
'from' acts as a link.
Can you help me to learn more?
(Other definitions for mask that I've seen before include "Domino" , "Cover for the face" , "One hiding, protecting face" , "Camouflage" , "Face covering; disguise" .)