Examine top of soup tin (4)
I believe the answer is:
scan
'examine' is the definition.
(scanning is a kind of examining)
'top of soup tin' is the wordplay.
'top of' suggests taking the first letters.
'tin' becomes 'can' ('can' can be a synonym of 'tin').
The initial letter of 'soup' is 's'.
's'+'can'='SCAN'
(Other definitions for scan that I've seen before include "Browse or skin over, say book" , "Examine intensely -- examine superficially" , "Analyse a piece of verse for metre" , "Traverse with a detector" , "Glance at or read quickly" .)