Examines small tins (5)
I believe the answer is:
scans
'examines' is the definition.
(scanning is a kind of examining)
'small tins' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'tins' becomes 'cans' ('can' can be a synonym of 'tin').
's'+'cans'='SCANS'
(Other definitions for scans that I've seen before include "medical examinations" , "Glances over" , "CAT and PET" , "CAT and MRI" .)