Enter lair in advance, with serious intent (9)
I believe the answer is:
earnestly
'with serious intent' is the definition.
(I've seen this before)
'enter lair in advance' is the wordplay.
'enter lair' becomes 'nest' (I can't justify this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'advance' becomes 'early' (similar in meaning).
'nest' inserted within 'early' is 'EARNESTLY'.
Can you help me to learn more?
(Other definitions for earnestly that I've seen before include "Relent, say, in sincere and serious manner" , "how Wilde character may be acted?" , "In all seriousness" , "Sincerely and seriously" , "Showing commitment" .)
