Despite rejection, fool starts to say thanks in passing (15)
I believe the answer is:
notwithstanding
'despite' is the definition.
(I've seen this before)
'rejection fool starts to say thanks in passing' is the wordplay.
I cannot really understand how this works, but
'fool' could be 'twit' (both can mean a stupid person) and 'twit' is located in the answer.
'thanks' could be 'ta' (UK informal version of 'thank you') and 'ta' is present in the answer.
'in' is within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for notwithstanding that I've seen before include "Nevertheless" , "Despite" , "anyway" , "yet" , "... in spite" .)