...to experience initial excitement in new ground (7)
I believe the answer is:
undergo
'to experience' is the definition.
('undergo' can be a synonym of 'experience')
'initial excitement in new ground' is the wordplay.
'initial' suggests taking the first letters.
'in' is an insertion indicator.
'new' indicates an anagram.
The first letter of 'excitement' is 'e'.
'ground' with letters rearranged gives 'undrgo'.
'e' inserted into 'undrgo' is 'UNDERGO'.
(Other definitions for undergo that I've seen before include "Guerdon (anag.)" , "Experience, be subjected to" , "Experience or live through" , "Suffer, experience" , "having to travel by tube" .)