Claim to know who ? Pardon me if doubtful (4-4)
I believe the answer is:
name-drop
'claim' is the definition.
Both the definition and answer are verbs in their base form.
Perhaps you can see an association between them that I don't see?
'know who ? pardon me if doubtful' is the wordplay.
'pardon me' anagrams to 'NAME-DROP'.
However, I am unsure how the anagram is indicated.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for name-drop that I've seen before include "Boast of acquaintance" , "Mention familiarity with famous people to impress" , "Mention important acquaintances" , "Mention celebrities as friends" , "Refer to famous people in familiar way to impress" .)