Shot on the way to an assignation (5)
I believe the answer is:
tryst
'an assignation' is the definition.
(synonyms)
'shot on the way' is the wordplay.
'shot' becomes 'try' (I've seen this before).
'on' means one lot of letters go next to another.
'the way' becomes 'st'.
'try'+'st'='TRYST'
'to' acts as a link.
(Other definitions for tryst that I've seen before include "An archaic lovers' meeting" , "meeting-place" , "Date" , "Romantic meeting" , "Rendezvous with lover" .)