Observed some Chinese engineers (4)
I believe the answer is:
seen
'observed' is the definition.
(synonyms)
'some chinese engineers' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'SEEN' is hidden within 'chinese engineers'.
(Other definitions for seen that I've seen before include "Spotted" , "Perceived by sight" , "Sighted" , "Espied" , "Met - understood" .)