Song about Zulu that’s work-shy (4)
I believe the answer is:
lazy
'work-shy' is the definition.
(synonyms)
'song about zulu' is the wordplay.
'song' becomes 'lay' (lay is a kind of song).
'about' means one lot of letters goes inside another.
'zulu' becomes 'Z' (phonetic alphabet: alpha, bravo, charlie etc.).
'lay' enclosing 'z' is 'LAZY'.
'that's' is the link.
(Other definitions for lazy that I've seen before include "Idle - indolent" , "avoiding work" , "Averse to exertion" , "Disinclined to work" , "Averse to labour" .)