Those people with eyes peeled? (4)
I believe the answer is:
they
'those people' is the definition.
('they' refers to a group of people)
'with eyes peeled?' is the wordplay.
'peeled?' indicates the answer is hidden within the clue (some letters peeled off to reveal the answer).
'THEY' is hidden within 'with eyes'.
(Other definitions for they that I've seen before include "Pronoun for people" , "Do -- Know It's Christmas (Band Aid)" , "People in general" , "Pronoun for more than one" , "Those people (vb. subject)" .)