Finding last bit and dashing off (7)
I believe the answer is:
tracing
'finding last bit' is the definition.
'tracing' can be an answer for 'finding' (I've seen this before). I am not certain of the 'last bit' bit.
'dashing off' is the wordplay.
I cannot really understand how this works, but
'dashing' could be 'racing' (I've seen this before) and 'racing' is located in the answer.
A single letter 't' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
'and' is the link.
Can you help me to learn more?
(Other definitions for tracing that I've seen before include "Finding by investigation" , "produce copy?" , "Hunting down" , "design" , "Tracking or outlining on transparent paper" .)