Student stops engineer working in shade
I believe the answer is:
nile green
'shade' is the definition.
(I have seen 'A shade' mean 'nile green' so perhaps 'shade' could also mean 'nile green')
'student stops engineer working' is the wordplay.
'student' becomes 'l' (as in L-plates for learner drivers).
'stops' means one lot of letters goes inside another.
'working' is an anagram indicator.
'engineer' is an anagram of 'niegreen'.
'l' going within 'niegreen' is 'NILE GREEN'.
'in' acts as a link.
(Other definitions for nile green that I've seen before include "Pale colour" , "Pale shade" .)