A leader of Zulus in tough venture (6)
I believe the answer is:
hazard
'venture' is the definition.
(both can mean to offer or suggest)
'a leader of zulus in tough' is the wordplay.
'leader of' suggests taking the first letters.
'in' indicates putting letters inside.
'tough' becomes 'hard' (associated in meaning).
The first letter of 'zulus' is 'z'.
'a'+'z'='az'
'az' placed into 'hard' is 'HAZARD'.
(Other definitions for hazard that I've seen before include "Risk; guess" , "Obstacle, source of danger" , "Endanger, jeopardize" , "Possible source of danger" , "Difficulty" .)