Tin with silver catch (4)
I believe the answer is:
snag
'catch' is the definition.
(snagging is a kind of catching)
'tin with silver' is the wordplay.
'tin' becomes 'Sn' (Sn is the chemical symbol for tin).
'with' is a charade indicator (letters next to each other).
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'sn'+'ag'='SNAG'
(Other definitions for snag that I've seen before include "Tear - catch" , "Hitch, unexpected problem" , "Rip or tear" , "Hidden obstacle or drawback" , "Hidden obstacle or catch" .)