Steer clear of social worker introducing great conflict (6)
I believe the answer is:
beware
'steer clear of' is the definition.
(to beware can mean to carefully avoid)
'social worker introducing great conflict' is the wordplay.
'social worker' becomes 'bee' (bees work socially).
'introducing' indicates putting letters inside (some letters introduced or inserted into others).
'great conflict' becomes 'war' (a war is a prolonged conflict).
'bee' enclosing 'war' is 'BEWARE'.
(Other definitions for beware that I've seen before include "Have caution, be on guard" , "Word of warning" , "Cry of warning" , "Stay alert to danger" , "Steer clear of" .)