Enquire like a king (3)
I believe the answer is:
ask
'enquire' is the definition.
(synonyms)
'like a king' is the wordplay.
'like' becomes 'as'.
'a king' becomes 'K' (abbreviation for king in chess).
'as'+'k'='ASK'
(Other definitions for ask that I've seen before include "Invite (to a party)" , "Issue invitations" , "Put a question" , "Pose" , "Inquire" .)