Declaring as evidence of examination into strange giant (9)
I believe the answer is:
attesting
'declaring' is the definition.
(attesting is a kind of declaring)
'examination into strange giant' is the wordplay.
'examination' becomes 'test' (synonyms).
'into' means one lot of letters goes inside another.
'strange' indicates anagramming the letters.
'giant' anagrammed gives 'ating'.
'test' going into 'ating' is 'ATTESTING'.
'as evidence of' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for attesting that I've seen before include "Declaring that something is the case" , "Witnessing" , "being a witness" .)