Afternoon essentially spent travelling west, bound to be exhausted (7)
I believe the answer is:
emptied
'be exhausted' is the definition.
(I've seen this before)
'afternoon essentially spent travelling west bound' is the wordplay.
'afternoon' becomes 'pm'.
'essentially' means to look at the middle letters.
'travelling west' says the letters should be written in reverse.
'bound' becomes 'tied' ('tie' can be a synonym of 'bind').
The centre of 'spent' is 'e'.
'pm'+'e'='pme'
'pme' written backwards gives 'emp'.
'emp'+'tied'='EMPTIED'
'to' is the link.
(Other definitions for emptied that I've seen before include "Drained" , "Vacated" , "having nothing more to offer" , "Removed the contents" , "gutted" .)