Like for example in a test (5)
I believe the answer is:
assay
'test' is the definition.
(I know that assay is a type of test)
'like for example' is the wordplay.
'like' becomes 'as'.
'for example' becomes 'say' ('say' can be used to introduce an example).
'as'+'say'='ASSAY'
'in a' is the link.
(Other definitions for assay that I've seen before include "Test ore for value" , "Evaluate" , "Test for metal content" , "Test the purity of metals" , "Test quality of ore" .)